openzeppelin-contracts/contracts/token/ERC20/SafeERC20.sol

pragma solidity ^0.4.24;

import "./ERC20Basic.sol";
import "./ERC20.sol";


/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure.
 * To use this library you can add a `using SafeERC20 for ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
  function safeTransfer(ERC20Basic _token, address _to, uint256 _value) internal {
    require(_token.transfer(_to, _value));
  }

  function safeTransferFrom(
    ERC20 _token,
    address _from,
    address _to,
    uint256 _value
  )
    internal
  {
    require(_token.transferFrom(_from, _to, _value));
  }

  function safeApprove(ERC20 _token, address _spender, uint256 _value) internal {
    require(_token.approve(_spender, _value));
  }
}