input: Write a function to calculate the factorial of a given integer. The function should take an integer as input and return the factorial of that integer. Implement the function using recursion. Additionally, write an input block that prompts the user to enter a number and then prints out the factorial of that number.
  assert factorial(7)==5040
  assert factorial(0)==1
  assert factorial(1)==1
  assert factorial(5)==120
  assert factorial(-3)==1
  
  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))
output: def factorial(num):
      if num <= 1:
          return 1
      else:
          return num * factorial(num - 1)