>>> class A:
...     SOME_CONSTANT = 8
...     print(str(SOME_CONSTANT))
...
8
>>> class A:
...     SOME_CONSTANT = 8
...     def go(self):
...             print(str(SOME_CONSTANT))
...
>>> a = A()
>>> a.go()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in go
NameError: global name 'SOME_CONSTANT' is not defined
>>>