input: def SumOfDigits(num: int) -> int:
      """
      Calculate the sum of the digits of a given number.
      Example:
      >>> SumOfDigits(6342)
      15
      """
      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
  