input: 
  def sum_list(input_list):
      """Calculates the sum of the items in the given list.
      >>> sum_list([1, 2, 3, 4])
      10
      >>> sum_list([-1, 0, 1])
      0
      >>> sum_list([10, 20, 30, 40])
      100
      """
      sum = 0
      for i in input_list:
          sum += i
      return sum
  
output:     sum = 0
      for i in input_list:
          sum += i
      return sum