class A:
     def __init__(self):
          self.a='a'


#A.m=lambda self, x: x*2

a=A()
a.v=lambda self, x: x*2


>>> a.v(z, 2)
Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
    a.v(z, 2)
NameError: name 'z' is not defined

>>> a.v(b, 2)
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    a.v(b, 2)
NameError: name 'b' is not defined

>>> b='b'
>>> a.v(b, 2)
4
>>> a.v("self", 2)
4
>>> a.v(1, 2)
4

>>> class A:
...   pass
... 
>>> A.m = lambda self, x: x * 2
>>> 
>>> a = A()
>>> a.m
<bound method A.<lambda> of <__main__.A object at 0xb759ae2c>>
>>> a.m(3)
6
>>> a.m(1, 3)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: <lambda>() takes exactly 2 positional arguments (3 given)
>>>