simpleReceiver.md

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

contract simpleReceiver{

function onERC721Received(
        address,
        address,
        uint256,
        bytes calldata
    ) external pure returns (bytes4){  
      // YOU CAN DO ANYTHING YOU WANT HERE 
      
      // THEN RETURN SELECTOR
        return this.onERC721Received.selector;
    }
}