def __add__(self, add_ordinate):
        """ Add two coordinates to each other, return new coordinate. """
        self._is_coordinate(add_ordinate)
        x = self.x + add_ordinate.x
        y = self.y + add_ordinate.y
        return self.__class__(x, y)
def __add__ ( self , add_ordinate ) : self . _is_coordinate ( add_ordinate ) x = self . x + add_ordinate . x y = self . y + add_ordinate . y return self . __class__ ( x , y )
Add two coordinates to each other, return new coordinate.