module mux2( z, Select, in0, in1); // two input one output mux
    input Select, in0, in1;
    output z;
    reg z;
always @(*)
    if (Select == 1'b1) // if not select branch
        z = in1;
    else if (Select == 1'b0)
        z = in0;
    else // else reset
        z = 1'bx;
endmodule