Tricky question Python

gistfile1.py

class A:
    def __init__(self):
        # self = B instance, when mangled, __value is replaced 
        # by _CurrentClass__value , so self.__dict__['_A__value'] = 1
        self.__value = 1  
        self.__a = 123

    def getvalue(self):
        print self.__a  # OK
        return self.__value  # Error - because of assignment in B.__init__
 
class B( A ):
    def __init__(self):
        A.__init__(self)
        self.__value = 2  # self.__dict__['_B__value'] = 2

b = B()
print b.getvalue() == b.__value  # Can't reference __value in b