In [10]: class A(object): pass
   ....:

In [11]: def f(self, x): print 'f called:', self, x
   ....:

In [12]: A.f = f

In [13]: a = A()

In [14]: a.f(2)
f called: <__main__.A object at 0x1b6a910> 2

In [15]: a.f.__f
a.f.__format__  a.f.__func__

In [15]: a.f.__func__.__name__
Out[15]: 'f'

In [16]: a.__class__
Out[16]: <class '__main__.A'>

In [17]: a.__class__.__name__
Out[17]: 'A'

In [18]: dir(a)
Out[18]:
['__class__',
 '__delattr__',
 '__dict__',
 '__doc__',
 '__format__',
 '__getattribute__',
 '__hash__',
 '__init__',
 '__module__',
 '__new__',
 '__reduce__',
 '__reduce_ex__',
 '__repr__',
 '__setattr__',
 '__sizeof__',
 '__str__',
 '__subclasshook__',
 '__weakref__',
 'f']

In [19]: del A.f

In [20]: a.f()
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)

/home/me/<ipython console> in <module>()

AttributeError: 'A' object has no attribute 'f'