input: def avg_list(lst: List[float]) -> float:
      """Calculate the average of a list of numbers.
      >>> avg_list([1.0, 2.0, 3.0])
      2.0
      >>> avg_list([5.0, 10.0, 15.0, 20.0])
      12.5
      >>> avg_list([])
      Traceback (most recent call last):
          ...
      ZeroDivisionError: division by zero
      """
output:     if not lst:
          raise ZeroDivisionError("division by zero")
      return sum(lst) / len(lst)