44. Bus Error Checker

How do you plan to solve it?

module error_checker_xz(
    input  [7:0] bus,
    output all_known, has_unknown,
    output [7:0] bus_if_known
);

    wire   any_xz = (^(bus^bus) === 1'bx);

    assign all_known    = ~any_xz;
    assign has_unknown  = any_xz;
    assign bus_if_known = (all_known==1'b1)? bus : 8'h00;

endmodule