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 xz = (^(bus ^ bus)) === 1'bx;
assign has_unknown = xz;
assign all_known = ~xz;
assign bus_if_known = {8{all_known}} & bus;

endmodule