#!/usr/local/bin/python2
import cPickle as pickle

class C(object):
  def __init__(self, a):
    self.a = a

c = C([3])
c4 = c
z = pickle.dumps(c)
c2 = pickle.loads(z)
c3 = pickle.loads(z)
print id(c), id(c2), id(c3), id(c4)

c2.a.append(2)
c.a.append(4)
print c.a, c2.a, c3.a, c4.a