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 has_xz = ^{bus,bus} === 1'bx;
    assign has_unknown = (has_xz);
    assign all_known = (!has_unknown);
    assign bus_if_known = (all_known)? bus : 0;

endmodule