input: def understand_recursion():
      """
      Develop a Python program to clearly understand the concept of recursion.
      This program defines a recursive function to calculate the factorial of a number.
      >>> result = factorial(5)
      >>> print("Factorial of 5 is ", result)
      Factorial of 5 is 120
      """
      def factorial(n):
          if n == 1:
              return 1
          else:
              return n * factorial(n - 1)
  
      result = factorial(5)
      print("Factorial of 5 is ", result)
output:     def factorial(n):
          if n == 1:
              return 1
          else:
              return n * factorial(n - 1)
  
      result = factorial(5)
      print("Factorial of 5 is ", result)