Using Verilog or VHDL programming, design and implement a digital system to perform addition or subtraction based on the choice of the user. You may consider the system to have two $4-$bit inputs $($i$.$e$.$ A and B$)$ and two outputs $($C and D$),$

here D is a $4-$bit binary number and C is one bit. There should be an additional input to choose the operation $($add or subtract!$).$