...s tools for smart contract engineers to use. They have some defaults, like ERC20 and ERC721 tools, where you can just import their contract and have a token built in seconds. Look how simple it is to make an ERC20 with OpenZeppelin:
[OpenZeppelin是](https://openzeppelin.com/contracts/)一个平台...
...EIP-712离线签名投票的方法。它的思路与我们之前讨论的ERC-20-Permit是一样的，可以参考阅读[无需gas代币的ERC20-Permit](https://learnblockchain.cn/article/1790)。
```javascript
function castVote(
uint proposalId,
bool support
)
function castVoteBySig(...