Write a test class called FilterTestCase(unittest. TestCase):, that is inheriting from unittest. TestCase and use the patch decorator and call methods of the mock object in unittest. In this class you should mock out the filter_num(v) function to return only 9 for every element in the list comprehension.

Asequential circuit contains a register of four flip-flops. initially a binary number n (0000 ≤ n ≤ 1100) is stored in the flip-flops. after a single clock pulse is applied to the circuit, the register should contain n + 0011. in other words, the function of the sequential circuit is to add 3 to the contents of a 4-bit register. design and implement this circuit using j-k flip-flops.