Reviews #115814 (comment), #115814 (comment), and #115814 (comment) show that there are a few things to refactor and/or optimize in regard to operators.
Furthermore, the documentation is sometimes rather hard to read without quotes, such as e.g., "Same as a is None." (which would be much better as "Same as 'a is None'." like @sobolevn proposed).

TODO:

• Optimize C implementations as e.g., shown in gh-115808: Add is_none and is_not_none operators #115814 (comment)
• Rephrase documentation as e.g., shown in gh-115808: Add is_none and is_not_none operators #115814 (comment) and gh-115808: Add is_none and is_not_none operators #115814 (comment)