How important is Python 1.5 compatibility?

[Josef Meile]

> How important do people think Python 1.5 compatibility is?
I think one as developer has to understand that the languages are 
evolving every day, so, one has to update the code as well and take 
advantages of the introduced features.

For example, consider working with strings:

in python 2.x you can say:
pos=myString.find('test')

on 1.5.x you can't do that. You have to do:

from string import find
pos=find(myString,'test')

I find the latest sintax is ugly and not object oriented. For style 
matters, I would switch to python 2.1.x

Regards,
Josef