input: Write a function to take an integer as input and print out its factorial. The function should be named factorial and should recursively calculate the factorial of the given number. If the input number is less than or equal to 1, the function should return 1. The final output should be printed using the print function. 
  
  n = int(input("Enter a number: "))  
  print("Factorial of",n,"is",factorial(n))
  
  assert factorial(7)==5040
  assert factorial(0)==1
  assert factorial(1)==1
  assert factorial(5)==120
  assert factorial(-1)==1
output: def factorial(n):
      if n <= 1:
          return 1
      else:
          return n * factorial(n - 1)