input: from typing import List
  
  def calculate_sum_of_digits(number: int) -> int:
      """
      Given a number, this function calculates the sum of its digits.
      >>> calculate_sum_of_digits(6342)
      15
      >>> calculate_sum_of_digits(12345)
      15
      """
      total = 0
      for digit in str(number):
          total += int(digit)
      return total
output:     total = 0
      for digit in str(number):
          total += int(digit)
      return total