input: Write a function that implements the given Python class to calculate the sum of two integers. The function should instantiate an object of the class and then call the add method to return the sum of the integers.
  
  class Sum:
      def __init__(self, x, y):
          self.x = x
          self.y = y
          
      def add(self):
          return self.x + self.y
  
  def calculate_sum(x, y):
      s = Sum(x, y)
      return s.add()
  
  assert calculate_sum(3, 5) == 8
  assert calculate_sum(-2, 2) == 0
  assert calculate_sum(0, 0) == 0
  assert calculate_sum(10, -10) == 0
  assert calculate_sum(7, 3) == 10
output: def calculate_sum(x, y):
      s = Sum(x, y)
      return s.add()