Devise an algorithm to receive a positive number, n, and output all prime numbers that are smaller than n and have a digit 7. For example, if n is 100, the program should output 7, 17, 37, 47, 67, 71, 73, 79, and 97. Your solution should have a main algorithm and two sub-algorithms, let's call them prime(num) and has 7(num). You may reuse the prime sub-algorithm of Ex 5. You do not need to verify (e.g. by tracing) it though because you did it in Ex 5. You need to trace your has algorithm. You should provide pre-rd post conditions for all your 3 (sub)algorithms.