// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

abstract contract ReentrancyGuard {

  uint256 private _status;

  uint256 private constant _NOT_ENTERED = 1;

  uint256 private constant _ENTERED = 2;

  constructor() {

    _status = _NOT_ENTERED;

  }

  modifier nonReentrant() {

    require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

    _status = _ENTERED;

    _;

    _status = _NOT_ENTERED;

  }

}