old_contents: def sum_of_numbers_iterative(n):
      the_sum=0
      for i in range(n):
          the_sum += (i+1)
      return the_sum
  print(sum_of_numbers_iterative(5))
  
  #Too high a number give:
  #RecursionError: maximum recursion depth exceeded in comparison
  
new_contents: def sum_of_numbers_iterative(n):
      the_sum=0
      for i in range(n):
          the_sum += (i+1)
      return the_sum
  print(sum_of_numbers_iterative(int(input("Enter a number: "))))
  #5+4+3+2+1=15
  
  #Too high a number give:
  #RecursionError: maximum recursion depth exceeded in comparison
  
subject: add user input