检查是否是721

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/introspection/ERC165Checker.sol";
import "@openzeppelin/contracts/token/ERC721/IERC721.sol";

contract MyTokenCheck  {
    using ERC165Checker for address;

    bytes4 private InterfaceId_ERC721 = 0x80ac58cd;

    /**
     * @dev transfer an ERC721 token from this contract to someone else
     */
    function transferERC721(
        address token,
        address to,
        uint256 tokenId
    )
        public
    {
        require(token.supportsInterface(InterfaceId_ERC721), "IS_NOT_721_TOKEN");
        IERC721(token).transferFrom(address(this), to, tokenId);
    }
}