SyntaxWarning: "is not" with a literal. Did you mean "!="?

[clokep]

the low_mark comparison is not obviously an error. I get this warning running: python manage.py runserver

/var/venv/lib/python3.8/site-packages/queryset_sequence/init.py:255: SyntaxWarning: "is not" with a literal. Did you mean "!="?
if low_mark is not 0:

For this reason I did that change, maybe, not strictly necessary.

Originally posted by @alfredo-ardito in https://github.com/percipient/django-querysetsequence/issues/58#issuecomment-562550902

[clokep]

I don't see this when running tests on Python 3.7, questions I have:

• Is this a new warning?
• Why was this code originally written to use is not here? It seems wrong, will need to investigate more.

[clokep]

It looks like this code was originally added in dd3502822ec4b9616aae1b9baaf5342211c992d1, so it has always been that way.

[alfredo-ardito]

I guess this warning comes from Python 3.8 I'll investigate and let you know

[clokep]

Seems to be documented in the changelog:

The compiler now produces a SyntaxWarning when identity checks (is and is not) are used with certain types of literals (e.g. strings, numbers). These can often work by accident in CPython, but are not guaranteed by the language spec. The warning advises users to use equality tests (== and !=) instead. (Contributed by Serhiy Storchaka in bpo-34850.)

I believe your fix was correct to just change it to a !=!

[alfredo-ardito]

okay, good to know.

[clokep]

Thanks for reporting this!