ERC20transfer.sol

pragma solidity =0.4.22;
/* Bad */
contract BadERC20Token{
    function transfer(address to, uint value) external;
    //...
}

/* Better */
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/SafeERC20.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/IERC20.sol";
contract GoodERC20Token {
  using SafeERC20 for IERC20;
  IERC20 public _token;
	function transfer(address to, uint value) external {
		_token.transfer(to,value);
	}
}