input: 
  def calculate_average_of_five(numbers: List[float]) -> float:
      """ Calculate the average of five numbers provided by the user.
      >>> calculate_average_of_five([1.0, 2.0, 3.0, 4.0, 5.0])
      3.0
      >>> calculate_average_of_five([10.0, 10.0, 10.0, 10.0, 10.0])
      10.0
      """
      return sum(numbers) / len(numbers)
  
output:     if len(numbers) != 5:
          raise ValueError("The list must contain exactly five numbers.")