input: def calculate_average(nums: List[int]) -> float:
      """
      Calculate the average of five numbers entered by a user.
      >>> calculate_average([3, 6, 9, 12, 15])
      9.0
      >>> calculate_average([2, 4, 6, 8, 10])
      6.0
      """
      return sum(nums) / len(nums)
output:     return sum(nums) / len(nums)