input: def avg_list(lst: List[float]) -> float:
      """ Calculate the average of a list of numbers.
      >>> avg_list([1.0, 2.0, 3.0, 4.0, 5.0])
      3.0
      >>> avg_list([10.5, 20.3, 30.1, 40.7])
      25.4
      """
output:     return sum(lst) / len(lst)