input: from typing import List
  
  class SumOfDigits:
      """A class that takes a number and calculates the sum of its digits.
      >>> digit_sum = SumOfDigits(6342)
      >>> digit_sum.calculate_sum_of_digits()
      15
      """
      
      def __init__(self, num):
          self.num = num
      
      def calculate_sum_of_digits(self):
          total = 0
          for ch in str(self.num):
              total += int(ch)
          return total
output:     def calculate_sum_of_digits(self):
          total = 0
          for ch in str(self.num):
              total += int(ch)
          return total