A DD flip-flop is similar to a D flip-flop, except that the flip-flop can change state (Q⁺ = D) on both the rising edge and the falling edge of the clock input. The flip-flop has a direct reset input, R, and R = 0 resets the flip-flop to Q = 0 independent of the clock. Similarly, it has a direct set input, S, that sets the flip-flop to 1 independent of the clock. Write a Verilog description of a DD flip-flop.