89. Serial-In Parallel-Out Register

How do you plan to solve it?

module sipo4 (
    input        CLK,
    input        RST,
    input        serial_in,
    output reg [3:0] Q
);
    // Write your code here
always@(posedge CLK or posedge RST)
if(RST) Q<=4'b0000 ; 
else 
       Q<={serial_in,Q[3:1]} ; 
endmodule