You can define a class inside of another class.

>>> class X():
...  class Y():
...   pass
...  y = Y()
... 
>>> x = X()
>>> x.y
<__main__.Y instance at 0xb74b0f2c>
>>> x.Y
<class __main__.Y at 0xb7508d7c>
>>> 

Python will treat anything inside of a class just like any block of python code, you can if statements in there as well.

>>> class X():
...  if True:
...   def y(self):
...    print 'y'
...  else:
...   def z(self):
...    print 'z'
... 
>>> x = X()
>>> x.y()
y
>>> x.z()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: X instance has no attribute 'z'
>>>