Day 4: Token Transfer and Safe Transfer_
```
contract MyERC721 is SafeERC721 {
    // ...

    function transferFrom(address from, address to, uint256 tokenId) public {
        // Check if the token exists
        require(_exists(tokenId), "Token does not exist");

function safeTransferFrom(address from, address to, uint256 tokenId) public {
        transferFrom(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, ""), "Safe transfer failed");
    }
}

// Check if the from address is the owner of the token
        require(ownerOf(tokenId) == from, "From address is not the owner");

        // Check if the to address is a valid address
        require(to != address(0), "Invalid to address");

        // Transfer the token
        _transferFrom(from, to, tokenId);
    }