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

interface IERC165 {
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

interface IMyContract {
    function myFunction() external;
}

contract MyContract is IMyContract, IERC165 {
    function supportsInterface(bytes4 interfaceId) external view returns (bool) {
        return interfaceId == type(IMyContract).interfaceId || interfaceId == interfaceId == type(IERC165).interfaceId;
    }

    function myFunction() external {
        // do something
    }
}