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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Reflect it that `sys.lazy_modules` is no longer a flat set","articleBody":"# Bug report\n\n### Bug description:\n\n`sys.lazy_modules` is now a `dict[str, set[str]]`, not a flat set. There's some places in the stdlib code that incorrectly suggests the older invariant.\n\nMost notable example:\n\nhttps://github.com/python/cpython/blob/70da972f97ec799dc7d7ab069fe195455f2f81b2/Lib/test/test_import/test_lazy_imports.py#L457-L459\n\nThe PEP needs updating as well -- https://peps.python.org/pep-0810/#lazy-import-mechanism -- @DinoV, I think this is something you were working on, or is it open for contrib?\n\nI'm happy to pick this one up (i.e. fixing our code to reflect `sys.lazy_modules` is a dict) if you'd like that! (Please reassign otherwise.)\n\ncc @pablogsal @DinoV @brittanyrey @Yhg1s\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\n_No response_\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-146084\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/johnslavik","@type":"Person","name":"johnslavik"},"datePublished":"2026-02-20T23:17:35.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/145057/cpython/issues/145057"}