input: def understand_recursion(n):
      """Write a Python program to clearly understand the concept of recursion.
      Define a recursive function to calculate the factorial of a number and calculate
      the factorial of number 5.
      >>> understand_recursion(5)
      'Factorial of 5 is 120'
      """
output:     if n == 0 or n == 1:
          return 1
      else:
          return n * understand_recursion(n - 1)
  
      result = understand_recursion(n)
      return f'Factorial of {n} is {result}'