input: def sum_list(lst):
      """
      Takes a list of integers and returns the sum of all elements.
      >>> sum_list([1, 2, 3, 4, 5])
      15
      >>> sum_list([-1, -2, -3, -4, -5])
      -15
      """
      total = 0
      for num in lst:
          total += num
      return total
output:     total = 0
      for num in lst:
          total += num
      return total