Implement a 4-bit ALU that supports 2-extender (AE and LE) each extender has 4 functions. For AEarithmetic extender, the functions are Decrement, Addition, Subtraction, and Increment respectively. For LE Logical extender, the functions are Complement, AND bitwise, Buffer and OR bitwise. Your module should have the following I/O pins: inputs 4-bit A and B, 2-bit S, M and output 4-bit Sum, O and Cout. (pls see figure below). Design a test bench to verify the functionality of your ALU. Your test cases should show the following: 1 test case for Arithmetic extender displaying all 4 functions (10-20ns,20-30ns,30-40ns,40-50ns) 1 test case for Logical extender displaying all 4 functions (60-70ns,70-80,80-90,90-100 ) 1 test case for overflow (overflow=1) 100-110ns $finish