Class variables vs. instance variables in python

gistfile1.txt

>>> class Test(object):
...     var = 7
...     def __init__(self):
...         self.ivar = 2
... 
>>> t = Test()
>>> s = Test()
>>> t.__dict__
{'ivar': 2}
>>> t.var
7
>>> t.var = 8
>>> t.__dict__
{'var': 8, 'ivar': 2}
>>> t.var
8
>>> s.var
7
>>> Test.var = 10
>>> s.var
10
>>> x = Test()
>>> x.var
10
>>> t.var
8
>>> t.__dict__
{'var': 8, 'ivar': 2}
>>> s.__dict__
{'ivar': 2}