// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../ERC20.sol";

abstract contract ERC20Pausable is ERC20 {

  bool private _paused;

  event Paused(address account);

  event Unpaused(address account);

  modifier whenNotPaused() {

    require(!_paused, "ERC20Pausable: token transfer while paused");

    _;

  }

  modifier whenPaused() {

    require(_paused, "ERC20Pausable: not paused");

    _;

  }

  function pause() external whenNotPaused {

    _paused = true;

    emit Paused(msg.sender);

  }

  function unpause() external whenPaused {

    _paused = false;

    emit Unpaused(msg.sender);

  }

  // Override transfer functions to include `whenNotPaused` modifier.

}