input: Write a python function to sum the items of a list.
  assert sum_list_items([1, 2, 3, 4, 5]) == 15
  assert sum_list_items([10, 20, 30, 40, 50]) == 150
  assert sum_list_items([5, -2, 7, 0, 3]) == 13
output: def sum_list_items(lst):
      return sum(lst)