        bytes4 data = IERC721TokenReceiver(_to).onERC721Received(
            _sender,
            _from,
            _tokenId,

            // this is empty byte data that can be optionally passed to
            // the contract we're confirming is able to receive NFTs
            ""
        );

        require(
            data != IERC721TokenReceiver.onERC721Received.selector,
            "bad nft transfer received data"
        );
        require(
            data == IERC721TokenReceiver.onERC721Received.selector,
            "bad nft transfer received data"
        );
