python: how to attach a function as a method instance to an arbitrary object.

object_method_instance_attach.py

# how to attach a function as a method instance to an arbitrary object.

class person:
    def __init__ (self):
        self.name = ""
    def beast (self):
        if self.name == "pedram":
            return True
        else:
            return False
            
>>> pedram = person()
>>> pedram.name = "pedram"

>>> dave = person()
>>> dave.name = "dave"

>>> dave.beast()
False

pedram.beast()
True

def say (self, msg):
    print self.name, msg
    
>>> pedram.say = types.MethodType(say, pedram)
>>> pedram.say("yeeehaaa")
pedram yeeehaaa

>>> dave.say("yeeehaaa")
Traceback (most recent call last):
  File "<input>", line 1, in <module>
AttributeError: person instance has no attribute 'say'