44. Bus Error Checker

How do you plan to solve it?

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

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

assign has_unknown = any_xz;
assign all_known = ~any_xz;
assign bus_if_known = {8{all_known}}& bus;
endmodule