input: Write a function to calculate the factorial of a given integer input. If the input is less than or equal to 1, return 1. Otherwise, recursively calculate the factorial. After defining the function, prompt the user to input an integer and print the factorial of that integer.
  
  def factorial(num):
      if num <= 1:
          return 1
      else:
          return num * factorial(num - 1)
  
  n = int(input("Enter a number: "))  
  print("Factorial of",n,"is",factorial(n))
  
  assert factorial(7) == 5040
  assert factorial(1) == 1
  assert factorial(0) == 1
  assert factorial(5) == 120
  assert factorial(-3) == 1
output: def factorial(num):
      if num <= 1:
          return 1
      else:
          return num * factorial(num - 1)