44. Bus Error Checker

How do you plan to solve it?

/*Write your code here*/
module error_checker_xz(
    input [7:0] bus,
    output all_known,has_unknown,
    output [7:0] bus_if_known
);
    // wire any_xz=
    assign has_unknown=((^(bus^bus))===1'bx);
    assign all_known=(~has_unknown);
    assign bus_if_known=(all_known)?bus:8'd0;
endmodule