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 self = (^(bus ^ bus) === 1'bx);
    assign has_unknown = self;
    assign all_known = ~has_unknown;
    assign bus_if_known = all_known ? bus : 8'h00;
endmodule