ETH Price: $2,146.45 (-0.94%)

Transaction Decoder

Block:
11847751 at Feb-13-2021 10:28:02 AM +UTC
Transaction Fee:
0.003805008 ETH $8.17
Gas Used:
27,978 Gas / 136 Gwei

Account State Difference:

  Address   Before After State Difference Code
(Spark Pool)
129.268765910776928467 Eth129.272570918776928467 Eth0.003805008
0x81417BE3...68f039c53
2.272399454669197554 Eth
Nonce: 11281
2.268594446669197554 Eth
Nonce: 11282
0.003805008

Execution Trace

0xe34820500dcd2a2c3c4ce2c1cac561e30ede0dc7.9149bafe( )
  • AdminUpgradeabilityProxy.70a08231( )
    • FXF.balanceOf( account=0xe34820500dcd2a2c3C4ce2C1cAC561e30Ede0dC7 ) => ( 0 )
      File 1 of 2: AdminUpgradeabilityProxy
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.6.0;
      import './UpgradeabilityProxy.sol';
      /**
       * @title AdminUpgradeabilityProxy
       * @dev This contract combines an upgradeability proxy with an authorization
       * mechanism for administrative tasks.
       * All external functions in this contract must be guarded by the
       * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
       * feature proposal that would enable this to be done automatically.
       */
      contract AdminUpgradeabilityProxy is UpgradeabilityProxy {
        /**
         * Contract constructor.
         * @param _logic address of the initial implementation.
         * @param _admin Address of the proxy administrator.
         * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
         * It should include the signature and the parameters of the function to be called, as described in
         * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
         * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
         */
        constructor(address _logic, address _admin, bytes memory _data) UpgradeabilityProxy(_logic, _data) public payable {
          assert(ADMIN_SLOT == bytes32(uint256(keccak256('eip1967.proxy.admin')) - 1));
          _setAdmin(_admin);
        }
        /**
         * @dev Emitted when the administration has been transferred.
         * @param previousAdmin Address of the previous admin.
         * @param newAdmin Address of the new admin.
         */
        event AdminChanged(address previousAdmin, address newAdmin);
        /**
         * @dev Storage slot with the admin of the contract.
         * This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is
         * validated in the constructor.
         */
        bytes32 internal constant ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;
        /**
         * @dev Modifier to check whether the `msg.sender` is the admin.
         * If it is, it will run the function. Otherwise, it will delegate the call
         * to the implementation.
         */
        modifier ifAdmin() {
          if (msg.sender == _admin()) {
            _;
          } else {
            _fallback();
          }
        }
        /**
         * @return The address of the proxy admin.
         */
        function admin() external ifAdmin returns (address) {
          return _admin();
        }
        /**
         * @return The address of the implementation.
         */
        function implementation() external ifAdmin returns (address) {
          return _implementation();
        }
        /**
         * @dev Changes the admin of the proxy.
         * Only the current admin can call this function.
         * @param newAdmin Address to transfer proxy administration to.
         */
        function changeAdmin(address newAdmin) external ifAdmin {
          require(newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");
          emit AdminChanged(_admin(), newAdmin);
          _setAdmin(newAdmin);
        }
        /**
         * @dev Upgrade the backing implementation of the proxy.
         * Only the admin can call this function.
         * @param newImplementation Address of the new implementation.
         */
        function upgradeTo(address newImplementation) external ifAdmin {
          _upgradeTo(newImplementation);
        }
        /**
         * @dev Upgrade the backing implementation of the proxy and call a function
         * on the new implementation.
         * This is useful to initialize the proxied contract.
         * @param newImplementation Address of the new implementation.
         * @param data Data to send as msg.data in the low level call.
         * It should include the signature and the parameters of the function to be called, as described in
         * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
         */
        function upgradeToAndCall(address newImplementation, bytes calldata data) payable external ifAdmin {
          _upgradeTo(newImplementation);
          (bool success,) = newImplementation.delegatecall(data);
          require(success);
        }
        /**
         * @return adm The admin slot.
         */
        function _admin() internal view returns (address adm) {
          bytes32 slot = ADMIN_SLOT;
          assembly {
            adm := sload(slot)
          }
        }
        /**
         * @dev Sets the address of the proxy admin.
         * @param newAdmin Address of the new proxy admin.
         */
        function _setAdmin(address newAdmin) internal {
          bytes32 slot = ADMIN_SLOT;
          assembly {
            sstore(slot, newAdmin)
          }
        }
        /**
         * @dev Only fall back when the sender is not the admin.
         */
        function _willFallback() internal override virtual {
          require(msg.sender != _admin(), "Cannot call fallback function from the proxy admin");
          super._willFallback();
        }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.6.0;
      import './Proxy.sol';
      import '@openzeppelin/contracts/utils/Address.sol';
      /**
       * @title UpgradeabilityProxy
       * @dev This contract implements a proxy that allows to change the
       * implementation address to which it will delegate.
       * Such a change is called an implementation upgrade.
       */
      contract UpgradeabilityProxy is Proxy {
        /**
         * @dev Contract constructor.
         * @param _logic Address of the initial implementation.
         * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
         * It should include the signature and the parameters of the function to be called, as described in
         * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
         * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
         */
        constructor(address _logic, bytes memory _data) public payable {
          assert(IMPLEMENTATION_SLOT == bytes32(uint256(keccak256('eip1967.proxy.implementation')) - 1));
          _setImplementation(_logic);
          if(_data.length > 0) {
            (bool success,) = _logic.delegatecall(_data);
            require(success);
          }
        }  
        /**
         * @dev Emitted when the implementation is upgraded.
         * @param implementation Address of the new implementation.
         */
        event Upgraded(address indexed implementation);
        /**
         * @dev Storage slot with the address of the current implementation.
         * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
         * validated in the constructor.
         */
        bytes32 internal constant IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
        /**
         * @dev Returns the current implementation.
         * @return impl Address of the current implementation
         */
        function _implementation() internal override view returns (address impl) {
          bytes32 slot = IMPLEMENTATION_SLOT;
          assembly {
            impl := sload(slot)
          }
        }
        /**
         * @dev Upgrades the proxy to a new implementation.
         * @param newImplementation Address of the new implementation.
         */
        function _upgradeTo(address newImplementation) internal {
          _setImplementation(newImplementation);
          emit Upgraded(newImplementation);
        }
        /**
         * @dev Sets the implementation address of the proxy.
         * @param newImplementation Address of the new implementation.
         */
        function _setImplementation(address newImplementation) internal {
          require(Address.isContract(newImplementation), "Cannot set a proxy implementation to a non-contract address");
          bytes32 slot = IMPLEMENTATION_SLOT;
          assembly {
            sstore(slot, newImplementation)
          }
        }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.6.0;
      /**
       * @title Proxy
       * @dev Implements delegation of calls to other contracts, with proper
       * forwarding of return values and bubbling of failures.
       * It defines a fallback function that delegates all calls to the address
       * returned by the abstract _implementation() internal function.
       */
      abstract contract Proxy {
        /**
         * @dev Fallback function.
         * Implemented entirely in `_fallback`.
         */
        fallback () payable external {
          _fallback();
        }
        /**
         * @dev Receive function.
         * Implemented entirely in `_fallback`.
         */
        receive () payable external {
          _fallback();
        }
        /**
         * @return The Address of the implementation.
         */
        function _implementation() internal virtual view returns (address);
        /**
         * @dev Delegates execution to an implementation contract.
         * This is a low level function that doesn't return to its internal call site.
         * It will return to the external caller whatever the implementation returns.
         * @param implementation Address to delegate.
         */
        function _delegate(address implementation) internal {
          assembly {
            // Copy msg.data. We take full control of memory in this inline assembly
            // block because it will not return to Solidity code. We overwrite the
            // Solidity scratch pad at memory position 0.
            calldatacopy(0, 0, calldatasize())
            // Call the implementation.
            // out and outsize are 0 because we don't know the size yet.
            let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
            // Copy the returned data.
            returndatacopy(0, 0, returndatasize())
            switch result
            // delegatecall returns 0 on error.
            case 0 { revert(0, returndatasize()) }
            default { return(0, returndatasize()) }
          }
        }
        /**
         * @dev Function that is run as the first thing in the fallback function.
         * Can be redefined in derived contracts to add functionality.
         * Redefinitions must call super._willFallback().
         */
        function _willFallback() internal virtual {
        }
        /**
         * @dev fallback implementation.
         * Extracted to enable manual triggering.
         */
        function _fallback() internal {
          _willFallback();
          _delegate(_implementation());
        }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity >=0.6.2 <0.8.0;
      /**
       * @dev Collection of functions related to the address type
       */
      library Address {
          /**
           * @dev Returns true if `account` is a contract.
           *
           * [IMPORTANT]
           * ====
           * It is unsafe to assume that an address for which this function returns
           * false is an externally-owned account (EOA) and not a contract.
           *
           * Among others, `isContract` will return false for the following
           * types of addresses:
           *
           *  - an externally-owned account
           *  - a contract in construction
           *  - an address where a contract will be created
           *  - an address where a contract lived, but was destroyed
           * ====
           */
          function isContract(address account) internal view returns (bool) {
              // This method relies on extcodesize, which returns 0 for contracts in
              // construction, since the code is only stored at the end of the
              // constructor execution.
              uint256 size;
              // solhint-disable-next-line no-inline-assembly
              assembly { size := extcodesize(account) }
              return size > 0;
          }
          /**
           * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
           * `recipient`, forwarding all available gas and reverting on errors.
           *
           * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
           * of certain opcodes, possibly making contracts go over the 2300 gas limit
           * imposed by `transfer`, making them unable to receive funds via
           * `transfer`. {sendValue} removes this limitation.
           *
           * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
           *
           * IMPORTANT: because control is transferred to `recipient`, care must be
           * taken to not create reentrancy vulnerabilities. Consider using
           * {ReentrancyGuard} or the
           * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
           */
          function sendValue(address payable recipient, uint256 amount) internal {
              require(address(this).balance >= amount, "Address: insufficient balance");
              // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
              (bool success, ) = recipient.call{ value: amount }("");
              require(success, "Address: unable to send value, recipient may have reverted");
          }
          /**
           * @dev Performs a Solidity function call using a low level `call`. A
           * plain`call` is an unsafe replacement for a function call: use this
           * function instead.
           *
           * If `target` reverts with a revert reason, it is bubbled up by this
           * function (like regular Solidity function calls).
           *
           * Returns the raw returned data. To convert to the expected return value,
           * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
           *
           * Requirements:
           *
           * - `target` must be a contract.
           * - calling `target` with `data` must not revert.
           *
           * _Available since v3.1._
           */
          function functionCall(address target, bytes memory data) internal returns (bytes memory) {
            return functionCall(target, data, "Address: low-level call failed");
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
           * `errorMessage` as a fallback revert reason when `target` reverts.
           *
           * _Available since v3.1._
           */
          function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
              return functionCallWithValue(target, data, 0, errorMessage);
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but also transferring `value` wei to `target`.
           *
           * Requirements:
           *
           * - the calling contract must have an ETH balance of at least `value`.
           * - the called Solidity function must be `payable`.
           *
           * _Available since v3.1._
           */
          function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
              return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
          }
          /**
           * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
           * with `errorMessage` as a fallback revert reason when `target` reverts.
           *
           * _Available since v3.1._
           */
          function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
              require(address(this).balance >= value, "Address: insufficient balance for call");
              require(isContract(target), "Address: call to non-contract");
              // solhint-disable-next-line avoid-low-level-calls
              (bool success, bytes memory returndata) = target.call{ value: value }(data);
              return _verifyCallResult(success, returndata, errorMessage);
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but performing a static call.
           *
           * _Available since v3.3._
           */
          function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
              return functionStaticCall(target, data, "Address: low-level static call failed");
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
           * but performing a static call.
           *
           * _Available since v3.3._
           */
          function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
              require(isContract(target), "Address: static call to non-contract");
              // solhint-disable-next-line avoid-low-level-calls
              (bool success, bytes memory returndata) = target.staticcall(data);
              return _verifyCallResult(success, returndata, errorMessage);
          }
          function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
              if (success) {
                  return returndata;
              } else {
                  // Look for revert reason and bubble it up if present
                  if (returndata.length > 0) {
                      // The easiest way to bubble the revert reason is using memory via assembly
                      // solhint-disable-next-line no-inline-assembly
                      assembly {
                          let returndata_size := mload(returndata)
                          revert(add(32, returndata), returndata_size)
                      }
                  } else {
                      revert(errorMessage);
                  }
              }
          }
      }
      

      File 2 of 2: FXF
      /*-
       * SPDX-License-Identifier: MIT
       *
       * Copyright (c) 2021, Fearless Legends Pte Ltd
       * All rights reserved.
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy
       * of this software and associated documentation files (the "Software"), to deal
       * in the Software without restriction, including without limitation the rights
       * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
       * copies of the Software, and to permit persons to whom the Software is
       * furnished to do so, subject to the following conditions:
       *
       * The above copyright notice and this permission notice shall be included in all
       * copies or substantial portions of the Software.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
       * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
       * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
       * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
       * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
       * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
       * SOFTWARE.
       *
       *
       * PLEASE READ THE TERMS SET OUT HEREIN CAREFULLY AND VERIFY ALL INFORMATION TO BE
       * CORRECT. THE AUTHORS OR COPYRIGHT HOLDERS SHALL NOT BE LIABLE FOR ANY INCORRECT
       * INFORMATION CONTAINED HEREIN.
       *
       * FXF TOKENS ARE NOT INTENDED TO CONSTITUTE SECURITIES OF ANY FORM, UNITS IN A
       * COLLECTIVE INVESTMENT SCHEME OR ANY OTHER FORM OF INVESTMENT IN ANY
       * JURISDICTION. THIS AGREEMENT DOES NOT CONSTITUTE A PROSPECTUS OR OFFER DOCUMENT
       * OF ANY SORT AND IS NOT INTENDED TO CONSTITUTE AN OFFER OF SECURITIES OF ANY
       * FORM, UNITS IN A COLLECTIVE INVESTMENT SCHEME OR ANY OTHER FORM OF INVESTMENT,
       * OR A SOLICITATION FOR ANY FORM OF INVESTMENT IN ANY JURISDICTION. NO REGULATORY
       * AUTHORITY HAS EXAMINED OR APPROVED THIS AGREEMENT, AND NO ACTION HAS BEEN OR
       * WILL BE TAKEN IN RESPECT OF OBTAINING SUCH APPROVAL UNDER THE LAWS, REGULATORY
       * REQUIREMENTS OR RULES OF ANY JURISDICTION.
       *
       * PLEASE NOTE THAT THE AUTHORS OR COPYRIGHT HOLDERS WILL NOT OFFER OR SELL TO
       * YOU, AND YOU ARE NOT ELIGIBLE TO PURCHASE ANY FXF TOKENS IF SUCH PURCHASE IS
       * PROHIBITED, RESTRICTED  OR UNAUTHORISED IN ANY FORM OR MANNER WHETHER IN FULL
       * OR IN PART UNDER THE LAWS, REGULATORY REQUIREMENTS OR RULES IN THE JURISDICTION
       * IN WHICH YOU ARE LOCATED OR SUBJECT TO.
       *
       * The Monetary Authority of Singapore (MAS) requires us to provide this risk
       * warning to you as a customer of a digital payment token (DPT) service provider.
       * Before you pay your DPT service provider any money or DPT, you should be aware
       * of the following.1.Your DPT service provider is exempted by MAS from holding a
       * license to provide DPT services. Please note that you may not be able to
       * recover all the money or DPTs you paid to your DPT service provider if your DPT
       * service provider’s business fails. 2.You should not transact in the DPT if you
       * are not familiar with this DPT. Transacting in DPTs may not be suitable for you
       * if you are not familiar with the technology that DPT services are
       * provided.3.You should be aware that the value of DPTs may fluctuate greatly.
       * You should buy DPTs only if you are prepared to accept the risk of losing all
       * of the money you put into such tokens.
       */
      pragma solidity >=0.7.6 <0.8.0;
      pragma abicoder v2;
      /*
      ███████╗██╗███╗   ██╗██╗  ██╗███████╗██╗      ██████╗     ███████╗██╗  ██╗███████╗
      ██╔════╝██║████╗  ██║╚██╗██╔╝██╔════╝██║     ██╔═══██╗    ██╔════╝╚██╗██╔╝██╔════╝
      █████╗  ██║██╔██╗ ██║ ╚███╔╝ █████╗  ██║     ██║   ██║    █████╗   ╚███╔╝ █████╗
      ██╔══╝  ██║██║╚██╗██║ ██╔██╗ ██╔══╝  ██║     ██║   ██║    ██╔══╝   ██╔██╗ ██╔══╝
      ██║     ██║██║ ╚████║██╔╝ ██╗██║     ███████╗╚██████╔╝    ██║     ██╔╝ ██╗██║
      ╚═╝     ╚═╝╚═╝  ╚═══╝╚═╝  ╚═╝╚═╝     ╚══════╝ ╚═════╝     ╚═╝     ╚═╝  ╚═╝╚═╝
      */
      import "@openzeppelin/contracts-upgradeable/token/ERC20/ERC20CappedUpgradeable.sol";
      import "@openzeppelin/contracts-upgradeable/math/SafeMathUpgradeable.sol";
      contract FXF is Initializable, ERC20Upgradeable, ERC20CappedUpgradeable {
          using SafeMathUpgradeable for uint256;
          address _governance;
          uint256 _version;
          /**
           * @dev deploy ERC20 token
           * @param name name of the token
           * @param symbol symbol of the token
           * @notice deployer is the governance
           */
          function initialize(string memory name, string memory symbol) public virtual initializer {
              __ERC20_init(name, symbol);
              __ERC20Capped_init(150 * 10**6 * 10**18);
              _mint(_msgSender(), 150 * 10**6 * 10**18);
              _governance = _msgSender();
              _version = 1;
          }
          struct LockInfo {
              address account;
              uint256 initialLockedTokens;
              uint256 lockedTokens;
              uint256[] amounts;
              uint256[] milestones;
              bool[] isClaimed;
              bool isLocked;
          }
          /**
           * @dev locking details
           */
          mapping (address => LockInfo) locks;
          /**
           * @dev Lock event triggered when an account is locked
           */
          event Lock(address account, uint256 amount);
          /**
           * @dev Unlock event triggered when an account unlocks tokens
           */
          event Unlock(address account, uint256 amount);
          /**
           * @dev lockInfo retreives the lock information of an account
           * @param account an account address
           * @return lock information for a given account
           */
          function lockInfo(address account) public view returns (LockInfo memory) {
              return locks[account];
          }
          /**
           * @dev isLocked is used to check the lock status of an account
           * @param account account to be checked
           */
          function isLocked(address account) public view returns (bool) {
              return locks[account].isLocked;
          }
          /**
           * @dev lockedTokens returns the number of locked tokens
           * @param account an account address
           * @return number of locked tokens for a given account
           */
          function lockedTokens(address account) public view returns (uint256) {
              return locks[account].lockedTokens;
          }
          /**
           * @dev Set Governance
           * @param governance_ the new governance
           * @notice can be set only by present governance address
           */
          function setGovernance(address governance_) public {
              require(_msgSender() == _governance, "!governance");
              require(governance_ != address(0), "governance can not be zero address");
              _governance = governance_;
          }
          /**
           * @dev unlockTokens is used by users to unlock tokens based on scheduled milestones
           */
          function unlockTokens() public {
              // Check if account has locked tokens
              require(isLocked(_msgSender()) == true, "Your wallet is not locked");
              // locking information
              LockInfo storage lock = locks[_msgSender()];
              // number of unlocked tokens
              uint256 unlockedTokens = 0;
              for (uint8 i = 0; i < lock.amounts.length; i++) {
                  if (block.timestamp >= lock.milestones[i] && lock.isClaimed[i] == false) {
                      unlockedTokens += lock.amounts[i];
                      lock.isClaimed[i] = true;
                  }
              }
              // update locked tokens
              lock.lockedTokens = lock.lockedTokens.sub(unlockedTokens);
              if(lock.lockedTokens == 0)
                  lock.isLocked = false;
              emit Unlock(_msgSender(), unlockedTokens);
          }
          /**
           * @dev transferLock transfer to a recipient and lock it's wallet.
           * @param recipient the account address to be locked
           * @param amount number of tokens to transfer and lock
           * @param amounts amounts of tokens to unlock after each milestone
           * @param milestones milestones when the tokens will be unlocked
           */
          function transferLock(address recipient, uint256 amount, uint256[] memory amounts, uint256[] memory milestones) public {
              // only governance can transfer and lock
              require(_msgSender() == _governance, "!governance");
              // Can't lock already locked wallet
              require(isLocked(recipient) == false, "Already Locked");
              // Can't lock address zero
              require(recipient != address(0), "The recipient's address cannot be 0");
              // Can't lock zero tokens
              require(amount > 0, "Amount has to be greater than 0");
              // number of amounts & number of milestones should be equal
              require(amounts.length == milestones.length, "Length of amounts & length of milestones must be equal");
              // sum of amounts should be equal to amount
              require(_sum(amounts) == amount, "Sum of amounts must equals to transfered amount");
              // init all claimed milestones to false
              bool[] memory isClaimed = _initArrayBool(milestones.length, false);
              // 1. lock
              locks[recipient] = LockInfo(recipient, amount, amount, amounts, milestones, isClaimed, true);
              // 2. transfer
              transfer(recipient, amount);
              // Lock event will be triggered
              emit Lock(recipient, amount);
          }
          /**
           * @dev _beforeTokenTransfer used override the check if the user is allowed to transfer the tokens or not
           */
          function _beforeTokenTransfer(address from, address to, uint256 amount) internal override (ERC20Upgradeable, ERC20CappedUpgradeable){
              super._beforeTokenTransfer(from, to, amount);
              // Check if the User is allowed to transfer the tokens or not
              require(_canTransfer(from, amount) == true, "Can not transfer locked tokens");
          }
          /**
           * @dev canTransfer used to check if the user is allowed to transfer the token or not
           * @param from account address of the user who wants to transfer
           * @param amount is the amount to planned to transfer
           */
          function _canTransfer(address from, uint256 amount) private view returns (bool) {
              if (isLocked(from) == true) {
                  uint256 transferable = balanceOf(from).sub(lockedTokens(from));
                  return (transferable >= amount);
              }
              return true;
          }
          /**
           * @dev _initArrayBool pure function is used to init an bool[]
           */
          function _initArrayBool(uint256 size, bool value) private pure returns (bool[] memory isClaimed) {
              isClaimed = new bool[](size);
              for (uint256 i = 0; i < size; i++) {
                  isClaimed[i] = value;
              }
              return isClaimed;
          }
          /**
           * @dev _sum pure function to sum elements in an array
           * @param array array of elements
           */
          function _sum(uint256[] memory array) private pure returns (uint256 sum) {
              sum = 0;
              for (uint8 i = 0; i < array.length; i++) {
                  sum += array[i];
              }
              return sum;
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity >=0.6.0 <0.8.0;
      /**
       * @dev Wrappers over Solidity's arithmetic operations with added overflow
       * checks.
       *
       * Arithmetic operations in Solidity wrap on overflow. This can easily result
       * in bugs, because programmers usually assume that an overflow raises an
       * error, which is the standard behavior in high level programming languages.
       * `SafeMath` restores this intuition by reverting the transaction when an
       * operation overflows.
       *
       * Using this library instead of the unchecked operations eliminates an entire
       * class of bugs, so it's recommended to use it always.
       */
      library SafeMathUpgradeable {
          /**
           * @dev Returns the addition of two unsigned integers, with an overflow flag.
           *
           * _Available since v3.4._
           */
          function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
              uint256 c = a + b;
              if (c < a) return (false, 0);
              return (true, c);
          }
          /**
           * @dev Returns the substraction of two unsigned integers, with an overflow flag.
           *
           * _Available since v3.4._
           */
          function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
              if (b > a) return (false, 0);
              return (true, a - b);
          }
          /**
           * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
           *
           * _Available since v3.4._
           */
          function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
              // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
              // benefit is lost if 'b' is also tested.
              // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
              if (a == 0) return (true, 0);
              uint256 c = a * b;
              if (c / a != b) return (false, 0);
              return (true, c);
          }
          /**
           * @dev Returns the division of two unsigned integers, with a division by zero flag.
           *
           * _Available since v3.4._
           */
          function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
              if (b == 0) return (false, 0);
              return (true, a / b);
          }
          /**
           * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
           *
           * _Available since v3.4._
           */
          function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
              if (b == 0) return (false, 0);
              return (true, a % b);
          }
          /**
           * @dev Returns the addition of two unsigned integers, reverting on
           * overflow.
           *
           * Counterpart to Solidity's `+` operator.
           *
           * Requirements:
           *
           * - Addition cannot overflow.
           */
          function add(uint256 a, uint256 b) internal pure returns (uint256) {
              uint256 c = a + b;
              require(c >= a, "SafeMath: addition overflow");
              return c;
          }
          /**
           * @dev Returns the subtraction of two unsigned integers, reverting on
           * overflow (when the result is negative).
           *
           * Counterpart to Solidity's `-` operator.
           *
           * Requirements:
           *
           * - Subtraction cannot overflow.
           */
          function sub(uint256 a, uint256 b) internal pure returns (uint256) {
              require(b <= a, "SafeMath: subtraction overflow");
              return a - b;
          }
          /**
           * @dev Returns the multiplication of two unsigned integers, reverting on
           * overflow.
           *
           * Counterpart to Solidity's `*` operator.
           *
           * Requirements:
           *
           * - Multiplication cannot overflow.
           */
          function mul(uint256 a, uint256 b) internal pure returns (uint256) {
              if (a == 0) return 0;
              uint256 c = a * b;
              require(c / a == b, "SafeMath: multiplication overflow");
              return c;
          }
          /**
           * @dev Returns the integer division of two unsigned integers, reverting on
           * division by zero. The result is rounded towards zero.
           *
           * Counterpart to Solidity's `/` operator. Note: this function uses a
           * `revert` opcode (which leaves remaining gas untouched) while Solidity
           * uses an invalid opcode to revert (consuming all remaining gas).
           *
           * Requirements:
           *
           * - The divisor cannot be zero.
           */
          function div(uint256 a, uint256 b) internal pure returns (uint256) {
              require(b > 0, "SafeMath: division by zero");
              return a / b;
          }
          /**
           * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
           * reverting when dividing by zero.
           *
           * Counterpart to Solidity's `%` operator. This function uses a `revert`
           * opcode (which leaves remaining gas untouched) while Solidity uses an
           * invalid opcode to revert (consuming all remaining gas).
           *
           * Requirements:
           *
           * - The divisor cannot be zero.
           */
          function mod(uint256 a, uint256 b) internal pure returns (uint256) {
              require(b > 0, "SafeMath: modulo by zero");
              return a % b;
          }
          /**
           * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
           * overflow (when the result is negative).
           *
           * CAUTION: This function is deprecated because it requires allocating memory for the error
           * message unnecessarily. For custom revert reasons use {trySub}.
           *
           * Counterpart to Solidity's `-` operator.
           *
           * Requirements:
           *
           * - Subtraction cannot overflow.
           */
          function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
              require(b <= a, errorMessage);
              return a - b;
          }
          /**
           * @dev Returns the integer division of two unsigned integers, reverting with custom message on
           * division by zero. The result is rounded towards zero.
           *
           * CAUTION: This function is deprecated because it requires allocating memory for the error
           * message unnecessarily. For custom revert reasons use {tryDiv}.
           *
           * Counterpart to Solidity's `/` operator. Note: this function uses a
           * `revert` opcode (which leaves remaining gas untouched) while Solidity
           * uses an invalid opcode to revert (consuming all remaining gas).
           *
           * Requirements:
           *
           * - The divisor cannot be zero.
           */
          function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
              require(b > 0, errorMessage);
              return a / b;
          }
          /**
           * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
           * reverting with custom message when dividing by zero.
           *
           * CAUTION: This function is deprecated because it requires allocating memory for the error
           * message unnecessarily. For custom revert reasons use {tryMod}.
           *
           * Counterpart to Solidity's `%` operator. This function uses a `revert`
           * opcode (which leaves remaining gas untouched) while Solidity uses an
           * invalid opcode to revert (consuming all remaining gas).
           *
           * Requirements:
           *
           * - The divisor cannot be zero.
           */
          function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
              require(b > 0, errorMessage);
              return a % b;
          }
      }
      // SPDX-License-Identifier: MIT
      // solhint-disable-next-line compiler-version
      pragma solidity >=0.4.24 <0.8.0;
      import "../utils/AddressUpgradeable.sol";
      /**
       * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
       * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
       * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
       * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
       *
       * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
       * possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.
       *
       * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
       * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
       */
      abstract contract Initializable {
          /**
           * @dev Indicates that the contract has been initialized.
           */
          bool private _initialized;
          /**
           * @dev Indicates that the contract is in the process of being initialized.
           */
          bool private _initializing;
          /**
           * @dev Modifier to protect an initializer function from being invoked twice.
           */
          modifier initializer() {
              require(_initializing || _isConstructor() || !_initialized, "Initializable: contract is already initialized");
              bool isTopLevelCall = !_initializing;
              if (isTopLevelCall) {
                  _initializing = true;
                  _initialized = true;
              }
              _;
              if (isTopLevelCall) {
                  _initializing = false;
              }
          }
          /// @dev Returns true if and only if the function is running in the constructor
          function _isConstructor() private view returns (bool) {
              return !AddressUpgradeable.isContract(address(this));
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity >=0.6.0 <0.8.0;
      import "./ERC20Upgradeable.sol";
      import "../../proxy/Initializable.sol";
      /**
       * @dev Extension of {ERC20} that adds a cap to the supply of tokens.
       */
      abstract contract ERC20CappedUpgradeable is Initializable, ERC20Upgradeable {
          using SafeMathUpgradeable for uint256;
          uint256 private _cap;
          /**
           * @dev Sets the value of the `cap`. This value is immutable, it can only be
           * set once during construction.
           */
          function __ERC20Capped_init(uint256 cap_) internal initializer {
              __Context_init_unchained();
              __ERC20Capped_init_unchained(cap_);
          }
          function __ERC20Capped_init_unchained(uint256 cap_) internal initializer {
              require(cap_ > 0, "ERC20Capped: cap is 0");
              _cap = cap_;
          }
          /**
           * @dev Returns the cap on the token's total supply.
           */
          function cap() public view virtual returns (uint256) {
              return _cap;
          }
          /**
           * @dev See {ERC20-_beforeTokenTransfer}.
           *
           * Requirements:
           *
           * - minted tokens must not cause the total supply to go over the cap.
           */
          function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override {
              super._beforeTokenTransfer(from, to, amount);
              if (from == address(0)) { // When minting tokens
                  require(totalSupply().add(amount) <= cap(), "ERC20Capped: cap exceeded");
              }
          }
          uint256[49] private __gap;
      }
      // SPDX-License-Identifier: MIT
      pragma solidity >=0.6.0 <0.8.0;
      import "../../utils/ContextUpgradeable.sol";
      import "./IERC20Upgradeable.sol";
      import "../../math/SafeMathUpgradeable.sol";
      import "../../proxy/Initializable.sol";
      /**
       * @dev Implementation of the {IERC20} interface.
       *
       * This implementation is agnostic to the way tokens are created. This means
       * that a supply mechanism has to be added in a derived contract using {_mint}.
       * For a generic mechanism see {ERC20PresetMinterPauser}.
       *
       * TIP: For a detailed writeup see our guide
       * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
       * to implement supply mechanisms].
       *
       * We have followed general OpenZeppelin guidelines: functions revert instead
       * of returning `false` on failure. This behavior is nonetheless conventional
       * and does not conflict with the expectations of ERC20 applications.
       *
       * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
       * This allows applications to reconstruct the allowance for all accounts just
       * by listening to said events. Other implementations of the EIP may not emit
       * these events, as it isn't required by the specification.
       *
       * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
       * functions have been added to mitigate the well-known issues around setting
       * allowances. See {IERC20-approve}.
       */
      contract ERC20Upgradeable is Initializable, ContextUpgradeable, IERC20Upgradeable {
          using SafeMathUpgradeable for uint256;
          mapping (address => uint256) private _balances;
          mapping (address => mapping (address => uint256)) private _allowances;
          uint256 private _totalSupply;
          string private _name;
          string private _symbol;
          uint8 private _decimals;
          /**
           * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
           * a default value of 18.
           *
           * To select a different value for {decimals}, use {_setupDecimals}.
           *
           * All three of these values are immutable: they can only be set once during
           * construction.
           */
          function __ERC20_init(string memory name_, string memory symbol_) internal initializer {
              __Context_init_unchained();
              __ERC20_init_unchained(name_, symbol_);
          }
          function __ERC20_init_unchained(string memory name_, string memory symbol_) internal initializer {
              _name = name_;
              _symbol = symbol_;
              _decimals = 18;
          }
          /**
           * @dev Returns the name of the token.
           */
          function name() public view virtual returns (string memory) {
              return _name;
          }
          /**
           * @dev Returns the symbol of the token, usually a shorter version of the
           * name.
           */
          function symbol() public view virtual returns (string memory) {
              return _symbol;
          }
          /**
           * @dev Returns the number of decimals used to get its user representation.
           * For example, if `decimals` equals `2`, a balance of `505` tokens should
           * be displayed to a user as `5,05` (`505 / 10 ** 2`).
           *
           * Tokens usually opt for a value of 18, imitating the relationship between
           * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
           * called.
           *
           * NOTE: This information is only used for _display_ purposes: it in
           * no way affects any of the arithmetic of the contract, including
           * {IERC20-balanceOf} and {IERC20-transfer}.
           */
          function decimals() public view virtual returns (uint8) {
              return _decimals;
          }
          /**
           * @dev See {IERC20-totalSupply}.
           */
          function totalSupply() public view virtual override returns (uint256) {
              return _totalSupply;
          }
          /**
           * @dev See {IERC20-balanceOf}.
           */
          function balanceOf(address account) public view virtual override returns (uint256) {
              return _balances[account];
          }
          /**
           * @dev See {IERC20-transfer}.
           *
           * Requirements:
           *
           * - `recipient` cannot be the zero address.
           * - the caller must have a balance of at least `amount`.
           */
          function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
              _transfer(_msgSender(), recipient, amount);
              return true;
          }
          /**
           * @dev See {IERC20-allowance}.
           */
          function allowance(address owner, address spender) public view virtual override returns (uint256) {
              return _allowances[owner][spender];
          }
          /**
           * @dev See {IERC20-approve}.
           *
           * Requirements:
           *
           * - `spender` cannot be the zero address.
           */
          function approve(address spender, uint256 amount) public virtual override returns (bool) {
              _approve(_msgSender(), spender, amount);
              return true;
          }
          /**
           * @dev See {IERC20-transferFrom}.
           *
           * Emits an {Approval} event indicating the updated allowance. This is not
           * required by the EIP. See the note at the beginning of {ERC20}.
           *
           * Requirements:
           *
           * - `sender` and `recipient` cannot be the zero address.
           * - `sender` must have a balance of at least `amount`.
           * - the caller must have allowance for ``sender``'s tokens of at least
           * `amount`.
           */
          function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
              _transfer(sender, recipient, amount);
              _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
              return true;
          }
          /**
           * @dev Atomically increases the allowance granted to `spender` by the caller.
           *
           * This is an alternative to {approve} that can be used as a mitigation for
           * problems described in {IERC20-approve}.
           *
           * Emits an {Approval} event indicating the updated allowance.
           *
           * Requirements:
           *
           * - `spender` cannot be the zero address.
           */
          function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
              _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
              return true;
          }
          /**
           * @dev Atomically decreases the allowance granted to `spender` by the caller.
           *
           * This is an alternative to {approve} that can be used as a mitigation for
           * problems described in {IERC20-approve}.
           *
           * Emits an {Approval} event indicating the updated allowance.
           *
           * Requirements:
           *
           * - `spender` cannot be the zero address.
           * - `spender` must have allowance for the caller of at least
           * `subtractedValue`.
           */
          function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
              _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
              return true;
          }
          /**
           * @dev Moves tokens `amount` from `sender` to `recipient`.
           *
           * This is internal function is equivalent to {transfer}, and can be used to
           * e.g. implement automatic token fees, slashing mechanisms, etc.
           *
           * Emits a {Transfer} event.
           *
           * Requirements:
           *
           * - `sender` cannot be the zero address.
           * - `recipient` cannot be the zero address.
           * - `sender` must have a balance of at least `amount`.
           */
          function _transfer(address sender, address recipient, uint256 amount) internal virtual {
              require(sender != address(0), "ERC20: transfer from the zero address");
              require(recipient != address(0), "ERC20: transfer to the zero address");
              _beforeTokenTransfer(sender, recipient, amount);
              _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
              _balances[recipient] = _balances[recipient].add(amount);
              emit Transfer(sender, recipient, amount);
          }
          /** @dev Creates `amount` tokens and assigns them to `account`, increasing
           * the total supply.
           *
           * Emits a {Transfer} event with `from` set to the zero address.
           *
           * Requirements:
           *
           * - `to` cannot be the zero address.
           */
          function _mint(address account, uint256 amount) internal virtual {
              require(account != address(0), "ERC20: mint to the zero address");
              _beforeTokenTransfer(address(0), account, amount);
              _totalSupply = _totalSupply.add(amount);
              _balances[account] = _balances[account].add(amount);
              emit Transfer(address(0), account, amount);
          }
          /**
           * @dev Destroys `amount` tokens from `account`, reducing the
           * total supply.
           *
           * Emits a {Transfer} event with `to` set to the zero address.
           *
           * Requirements:
           *
           * - `account` cannot be the zero address.
           * - `account` must have at least `amount` tokens.
           */
          function _burn(address account, uint256 amount) internal virtual {
              require(account != address(0), "ERC20: burn from the zero address");
              _beforeTokenTransfer(account, address(0), amount);
              _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
              _totalSupply = _totalSupply.sub(amount);
              emit Transfer(account, address(0), amount);
          }
          /**
           * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
           *
           * This internal function is equivalent to `approve`, and can be used to
           * e.g. set automatic allowances for certain subsystems, etc.
           *
           * Emits an {Approval} event.
           *
           * Requirements:
           *
           * - `owner` cannot be the zero address.
           * - `spender` cannot be the zero address.
           */
          function _approve(address owner, address spender, uint256 amount) internal virtual {
              require(owner != address(0), "ERC20: approve from the zero address");
              require(spender != address(0), "ERC20: approve to the zero address");
              _allowances[owner][spender] = amount;
              emit Approval(owner, spender, amount);
          }
          /**
           * @dev Sets {decimals} to a value other than the default one of 18.
           *
           * WARNING: This function should only be called from the constructor. Most
           * applications that interact with token contracts will not expect
           * {decimals} to ever change, and may work incorrectly if it does.
           */
          function _setupDecimals(uint8 decimals_) internal virtual {
              _decimals = decimals_;
          }
          /**
           * @dev Hook that is called before any transfer of tokens. This includes
           * minting and burning.
           *
           * Calling conditions:
           *
           * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
           * will be to transferred to `to`.
           * - when `from` is zero, `amount` tokens will be minted for `to`.
           * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
           * - `from` and `to` are never both zero.
           *
           * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
           */
          function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
          uint256[44] private __gap;
      }
      // SPDX-License-Identifier: MIT
      pragma solidity >=0.6.0 <0.8.0;
      /**
       * @dev Interface of the ERC20 standard as defined in the EIP.
       */
      interface IERC20Upgradeable {
          /**
           * @dev Returns the amount of tokens in existence.
           */
          function totalSupply() external view returns (uint256);
          /**
           * @dev Returns the amount of tokens owned by `account`.
           */
          function balanceOf(address account) external view returns (uint256);
          /**
           * @dev Moves `amount` tokens from the caller's account to `recipient`.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * Emits a {Transfer} event.
           */
          function transfer(address recipient, uint256 amount) external returns (bool);
          /**
           * @dev Returns the remaining number of tokens that `spender` will be
           * allowed to spend on behalf of `owner` through {transferFrom}. This is
           * zero by default.
           *
           * This value changes when {approve} or {transferFrom} are called.
           */
          function allowance(address owner, address spender) external view returns (uint256);
          /**
           * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * IMPORTANT: Beware that changing an allowance with this method brings the risk
           * that someone may use both the old and the new allowance by unfortunate
           * transaction ordering. One possible solution to mitigate this race
           * condition is to first reduce the spender's allowance to 0 and set the
           * desired value afterwards:
           * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
           *
           * Emits an {Approval} event.
           */
          function approve(address spender, uint256 amount) external returns (bool);
          /**
           * @dev Moves `amount` tokens from `sender` to `recipient` using the
           * allowance mechanism. `amount` is then deducted from the caller's
           * allowance.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * Emits a {Transfer} event.
           */
          function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
          /**
           * @dev Emitted when `value` tokens are moved from one account (`from`) to
           * another (`to`).
           *
           * Note that `value` may be zero.
           */
          event Transfer(address indexed from, address indexed to, uint256 value);
          /**
           * @dev Emitted when the allowance of a `spender` for an `owner` is set by
           * a call to {approve}. `value` is the new allowance.
           */
          event Approval(address indexed owner, address indexed spender, uint256 value);
      }
      // SPDX-License-Identifier: MIT
      pragma solidity >=0.6.2 <0.8.0;
      /**
       * @dev Collection of functions related to the address type
       */
      library AddressUpgradeable {
          /**
           * @dev Returns true if `account` is a contract.
           *
           * [IMPORTANT]
           * ====
           * It is unsafe to assume that an address for which this function returns
           * false is an externally-owned account (EOA) and not a contract.
           *
           * Among others, `isContract` will return false for the following
           * types of addresses:
           *
           *  - an externally-owned account
           *  - a contract in construction
           *  - an address where a contract will be created
           *  - an address where a contract lived, but was destroyed
           * ====
           */
          function isContract(address account) internal view returns (bool) {
              // This method relies on extcodesize, which returns 0 for contracts in
              // construction, since the code is only stored at the end of the
              // constructor execution.
              uint256 size;
              // solhint-disable-next-line no-inline-assembly
              assembly { size := extcodesize(account) }
              return size > 0;
          }
          /**
           * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
           * `recipient`, forwarding all available gas and reverting on errors.
           *
           * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
           * of certain opcodes, possibly making contracts go over the 2300 gas limit
           * imposed by `transfer`, making them unable to receive funds via
           * `transfer`. {sendValue} removes this limitation.
           *
           * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
           *
           * IMPORTANT: because control is transferred to `recipient`, care must be
           * taken to not create reentrancy vulnerabilities. Consider using
           * {ReentrancyGuard} or the
           * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
           */
          function sendValue(address payable recipient, uint256 amount) internal {
              require(address(this).balance >= amount, "Address: insufficient balance");
              // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
              (bool success, ) = recipient.call{ value: amount }("");
              require(success, "Address: unable to send value, recipient may have reverted");
          }
          /**
           * @dev Performs a Solidity function call using a low level `call`. A
           * plain`call` is an unsafe replacement for a function call: use this
           * function instead.
           *
           * If `target` reverts with a revert reason, it is bubbled up by this
           * function (like regular Solidity function calls).
           *
           * Returns the raw returned data. To convert to the expected return value,
           * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
           *
           * Requirements:
           *
           * - `target` must be a contract.
           * - calling `target` with `data` must not revert.
           *
           * _Available since v3.1._
           */
          function functionCall(address target, bytes memory data) internal returns (bytes memory) {
            return functionCall(target, data, "Address: low-level call failed");
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
           * `errorMessage` as a fallback revert reason when `target` reverts.
           *
           * _Available since v3.1._
           */
          function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
              return functionCallWithValue(target, data, 0, errorMessage);
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but also transferring `value` wei to `target`.
           *
           * Requirements:
           *
           * - the calling contract must have an ETH balance of at least `value`.
           * - the called Solidity function must be `payable`.
           *
           * _Available since v3.1._
           */
          function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
              return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
          }
          /**
           * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
           * with `errorMessage` as a fallback revert reason when `target` reverts.
           *
           * _Available since v3.1._
           */
          function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
              require(address(this).balance >= value, "Address: insufficient balance for call");
              require(isContract(target), "Address: call to non-contract");
              // solhint-disable-next-line avoid-low-level-calls
              (bool success, bytes memory returndata) = target.call{ value: value }(data);
              return _verifyCallResult(success, returndata, errorMessage);
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but performing a static call.
           *
           * _Available since v3.3._
           */
          function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
              return functionStaticCall(target, data, "Address: low-level static call failed");
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
           * but performing a static call.
           *
           * _Available since v3.3._
           */
          function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
              require(isContract(target), "Address: static call to non-contract");
              // solhint-disable-next-line avoid-low-level-calls
              (bool success, bytes memory returndata) = target.staticcall(data);
              return _verifyCallResult(success, returndata, errorMessage);
          }
          function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
              if (success) {
                  return returndata;
              } else {
                  // Look for revert reason and bubble it up if present
                  if (returndata.length > 0) {
                      // The easiest way to bubble the revert reason is using memory via assembly
                      // solhint-disable-next-line no-inline-assembly
                      assembly {
                          let returndata_size := mload(returndata)
                          revert(add(32, returndata), returndata_size)
                      }
                  } else {
                      revert(errorMessage);
                  }
              }
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity >=0.6.0 <0.8.0;
      import "../proxy/Initializable.sol";
      /*
       * @dev Provides information about the current execution context, including the
       * sender of the transaction and its data. While these are generally available
       * via msg.sender and msg.data, they should not be accessed in such a direct
       * manner, since when dealing with GSN meta-transactions the account sending and
       * paying for execution may not be the actual sender (as far as an application
       * is concerned).
       *
       * This contract is only required for intermediate, library-like contracts.
       */
      abstract contract ContextUpgradeable is Initializable {
          function __Context_init() internal initializer {
              __Context_init_unchained();
          }
          function __Context_init_unchained() internal initializer {
          }
          function _msgSender() internal view virtual returns (address payable) {
              return msg.sender;
          }
          function _msgData() internal view virtual returns (bytes memory) {
              this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
              return msg.data;
          }
          uint256[50] private __gap;
      }