input: Write a function to create a class for a 2D coordinate system that can calculate the magnitude of a coordinate and add two coordinates together.
  assert CoordinateSystem(3, 4).magnitude() == 5.0
  assert CoordinateSystem(1, 1).add(CoordinateSystem(2, 3)).x == 3
  assert CoordinateSystem(1, 1).add(CoordinateSystem(2, 3)).y == 4
output: import math
  
  class CoordinateSystem:
      def __init__(self, x, y):
          self.x = x
          self.y = y
  
      def magnitude(self):
          return math.sqrt(self.x**2 + self.y**2)
  
      def add(self, other):
          return CoordinateSystem(self.x + other.x, self.y + other.y)