>>> x = chr(13)
>>> y = chr(13)
>>> id(x), id(y)
(3082874688L, 3082874688L)
>>> x = chr(13) + chr(14)
>>> y = chr(13) + chr(14)
>>> id(x), id(y)
(3077159616L, 3077159584L)
>>> x = "a"*20
>>> y = "a"*20
>>> z = "a"*21
>>> w = "a"*21
>>> id(x), id(y), id(z), id(w)
(3079663488L, 3079663488L, 3079721328L, 3079721568L)