input: from typing import List
  
  def calculate_sum_of_digits(num: int) -> int:
      """Calculate the sum of digits of a given number.
      
      >>> calculate_sum_of_digits(6342)
      15
      >>> calculate_sum_of_digits(123)
      6
      """
      total = 0
      for ch in str(num):
          total += int(ch)
      return total
output:     total = 0
      for ch in str(num):
          total += int(ch)
      return total