contract.sol

// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.9.0;

enum A {
     X,Y,Z
}

contract K {

}

contract B is K {
    function isX(A a) public pure returns(uint256){
        if(a == A.X){
            return 1;
        }
        return 2;
    }

    function call(address z) public view returns(uint256){
        return B(z).isX(A.Y);
    }

    function a(K k) public pure {}
    // function a(address payable b) public pure {}
}


interface ISome {
    function a() external returns(K);
}

contract Some is ISome {

    // B public override a;
 
    function a() external override pure returns(K){
        return B(address(0));
    }
}