input: def factorial(num: int) -> int:
      """Calculate the factorial of a given integer using recursion.
      >>> factorial(0)
      1
      >>> factorial(1)
      1
      >>> factorial(5)
      120
      """
  
      if num <= 1:
          return 1
      else:
          return num * factorial(num - 1)
  
  n = int(input("Enter a number: "))
  print("Factorial of", n, "is", factorial(n))
output:     if num <= 1:
          return 1
      else:
          return num * factorial(num - 1)