input: Write a python function to create an instance of class B, modify its attribute x, and then return the modified value.
  assert modify_and_get_x(10, 5) == 6
  assert modify_and_get_x(20, 15) == 16
  assert modify_and_get_x(0, -10) == -9
output: class B:
      def __init__(self, x):
          self.x = x
  
  def modify_and_get_x(initial_x, modification):
      b = B(initial_x)
      b.x = modification + 1
      return b.x