input: def average_of_positive_integers(positive_integers: List[int]) -> float:
      """ Calculate the average of a list of positive integers and return the result.
      >>> average_of_positive_integers([1, 5, 6, 7, 8])
      5.4
      """
output:     if not positive_integers:
          return 0.0
      total = sum(positive_integers)
      count = len(positive_integers)
      return total / count