class foo( object ):
  class_var = []

  def __init__( self, n, m ):
     self.class_var.append( n + m )
     self.instance_var = []
     self.instance_var.append( n + m )

  def func( self, msg ):
     print msg, '- class var   :', self.class_var
     print msg, '- instance var:', self.instance_var

hoge = foo( 1, 2 )
hoge.func( 'hoge' )
fuga = foo( 3, 4 )
fuga.func( 'fuga' )
peko = foo( 5, 6 )
peko.func( 'peko' )

hoge - class var   : [3]
hoge - instance var: [3]
fuga - class var   : [3, 7]
fuga - instance var: [7]
peko - class var   : [3, 7, 11]
peko - instance var: [11]