Private variable tricks is not working in Python 3.6

private_not_working.py

class A:
    def __init__(self):
        self.__var1 = 123
        self.__dict__ = {}    # override to prevent peeking
                              # then randomize the pattern of private variable
                              # ie "_classname__variablename" is too obvious
    def printVar1(self):
        print(self.__var1)

x = A()
x.printVar1() #AttributeError: 'A' object has no attribute '_A__var1'