input: def sum_list(input_list):
      """
      Takes a list as input and returns the sum of the items in the list.
      >>> sum_list([1, 2, 3, 4])
      10
      >>> sum_list([10, -5, 3, 2])
      10
      >>> sum_list([])
      0
      """
output:     return sum(input_list)