class ThisIsAClass(object):
	somelameset = set()
	
	def add_something(self, stuff):
		self.somelameset.add(stuff)
		
###

jim = ThisIsAClass()
bob = ThisIsAClass()

jim.add_something("a string")

print "I wonder what's in here?", bob.somelameset

###
#
# I wonder what's in here? set(['a string'])
#