Change `== None` to `is None`

Editor assessment

The subject completely describes the code change, `== None` becoming `is None`, and the body supplies a cited rationale: an LGTM rule recommending the identity comparison, with a link. That elevates a trivial style fix into a documented decision, however small. The chore type fits a lint-driven sweep, no scope is needed for a mechanical replacement, and no footers appear. Hygiene is clean, with the backticked expressions making the diff expectation exact. A minor change communicated exactly as thoroughly as it needs to be, with nothing missing that matters.