Definitively! Thanks for bringing this up. Already spotted the very same thing when copying verbatim from the `if 'acceptable' in args:` implementation.

Will refactor both parts, right?

I'd write:

    contenttypes_supported.extend(request.info.get('contenttypes_supported', []))

To filter duplicates, maybe after that:

    contenttypes_supported = list(set(contenttypes_supported))