what does is ?

[Padraig Brady]

Gerhard Häring wrote:
> Jonas Geiregat <kemu at sdf-eu.org> wrote:
> 
>>I saw something
>>import string
>>string._StringType is str
>>what does this specially that IS
> 
> The "is" operator compares object *identity*, rather than equality, which the
> "==" operator does.

Well why does the following happen on 2.2?
Is Python being clever about merging variables?

s1="123"
s2=s1[:]
s1 is s2 #true?