Can access class private variable?

[snippsat]

You can access it bye hw._HWClass__classvar  not hw.__classvar.

>>> hw = HWClass()
>>> hw._HWClass__classvar
3
>>> hw._HWClass__classvar = 4
>>> hw._HWClass__classvar
4

As mention there is nothing private in Python.
__ would say it should not be used before understanding what's it's used for(name mangling).
A quick demo of name mangling.

class HWClass:
    def __init__(self):
        self.__classvar = 3 # Not private, it's for name mangling

class HW(HWClass):
    def __init__(self):
        super().__init__()
        self.__classvar = 3 

Now if use Class HW,
has class variable classvar been named mangled(not overwritten).

>>> hw = HW()
# Both have been given different name(name mangling)
>>> hw._HWClass__classvar
3
>>> hw._HW__classvar
3

# Change one will not change the other
>>> hw._HWClass__classvar = 100
>>> hw._HWClass__classvar
100
>>> hw._HW__classvar
3

It's take some chaining to learn it the Python way,when coming from Java.