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,
    output has_unknown,
    output [7:0]bus_if_known
);
wire flag=(^bus)===1'bx;
assign has_unknown=flag;
assign all_known=~flag;
assign bus_if_known={8{all_known}}&bus;

endmodule