import weakref
class cls1:
	def giveTo( self, to ):
		to.take( self.bla )
	def bla(self ):
		pass
		
class cls2:
	def take( self, what ):
		self.ref = weakref.ref(what)
		
c1 = cls1()
c2 = cls2()
c1.giveTo( c2 )
print c1.bla
print c2.ref