我正在阅读来自solidity的几个示例:文档。我遇到过这样的功能:
function claimPayment(uint256 amount, uint256 nonce, bytes memory signature) external {
require(!usedNonces[nonce]);
usedNonces[nonce] = true;
// this recreates the message that was signed on the client
bytes32 message = prefixed(ke