library AddressUtils
{

  /**
   * @dev Returns whether the target address is a contract.
   * @param _addr Address to check.
   * @return addressCheck True if _addr is a contract, false if not.
   */
  function isContract(
    address _addr
  )
    internal
    view
    returns (bool addressCheck)
  {
    // This method relies in extcodesize, which returns 0 for contracts in
    // construction, since the code is only stored at the end of the
    // constructor execution.

    // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
    // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
    // for accounts without code, i.e. `keccak256('')`
    bytes32 codehash;
    bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
    assembly { codehash := extcodehash(_addr) } // solhint-disable-line
    addressCheck = (codehash != 0x0 && codehash != accountHash);
  }

}
/**
 * @notice Based on:
 * https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Address.sol
 * Requires EIP-1052.
 * @dev Utility library of inline functions on addresses.
 */
function isContract(
  address _addr
)
  internal
  view
  returns (bool addressCheck)
{
  // This method relies in extcodesize, which returns 0 for contracts in
  // construction, since the code is only stored at the end of the
  // constructor execution.

  // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
  // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
  // for accounts without code, i.e. `keccak256('')`
  bytes32 codehash;
  bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
  assembly { codehash := extcodehash(_addr) } // solhint-disable-line
  addressCheck = (codehash != 0x0 && codehash != accountHash);
}

/**
 * @dev Returns whether the target address is a contract.
 * @param _addr Address to check.
 * @return addressCheck True if _addr is a contract, false if not.
 */