How to make rope aware that an instance attribute is of a certain type

Question

I am using Python 2.7 and want to do some refactoring using rope (via python-mode in vim).

I have a class containing the method I want to refactor and another class which has an instance attribute containing an instance of the first class.

Assume I want to change the name of Car.get_n_wheels() in the following example:

class Car(object):
    def __init__(self, n_wheels):
        self._n_wheels = n_wheels

    def get_n_wheels(self):
        return self._n_wheels


class Garage(object):

    def __init__(self, car):
        self._car = car       # with this line print_n_wheels is not refactored
        # self._car = Car(4)  # with this line print_n_wheels is refactored

    def print_n_wheels(self):
        ''''getter'''
        print self._car.get_n_wheels()

The last line is changed only if I explicitly enforce that _car is a car by creating a new Car object, but I want to hand a finished car object to the constructor.

Is there any way to tell rope what is the (expected) type of an instance variable?