input: 
  def average_of_positive_integers(numbers: List[int]) -> float:
      """ Calculate and return the average of a list of positive integers.
      >>> average_of_positive_integers([1, 5, 6, 7, 8])
      5.4
      >>> average_of_positive_integers([10, 20, 30, 40])
      25.0
      """
  
output:     positive_numbers = [num for num in numbers if num > 0]
      if not positive_numbers:
          return 0.0
      return sum(positive_numbers) / len(positive_numbers)