input: def SumOfDigits:
      """Construct a Python class that takes a given number and calculates the sum of the digits.
      
      Example:
      SumOfDigits(6342).calculate_sum_of_digits() == 15
      """
output:     
      def __init__(self, number):
          self.number = number
  
      def calculate_sum_of_digits(self):
          return sum(int(digit) for digit in str(self.number))
  