Consider the n-bit shift register circuit shown below:

Write a Verilog module named top_module for one stage of this circuit, including both the flip-flop and multiplexers.
module top_module (
    input clk,
    input w, R, E, L,
    output Q
);
	wire d;
    assign d=L? R:(E ? w:Q);
    always@(posedge clk) begin
       Q<=d;
    end
endmodule