input: 
  def calculate_average(nums: List[float]) -> float:
      """ Calculate the average of a list of numbers.
      >>> calculate_average([10.0, 20.0, 30.0, 40.0, 50.0])
      30.0
      >>> calculate_average([5.5, 6.6, 7.7, 8.8, 9.9])
      7.7
      """
      return sum(nums) / len(nums)
  
output:     return sum(nums) / len(nums)