我对solidity.Below很陌生,它是我遇到的可靠源代码的片段:-
pragma solidity ^0.5.1;
library SafeMath {
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
assert(b <= a); //error handling condition
return a - b;
}
function add(uint256 a, uint256 b) internal pure returns (