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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"mypy@0.920 regression: Argument 1 to \"get\" of \"Mapping\" has incompatible type","articleBody":"I got a new regression from the latest release on a real project: https://github.com/wemake-services/wemake-python-styleguide/blob/master/wemake_python_styleguide/logic/arguments/function_args.py#L125-L126\r\n\r\nError:\r\n\r\n```\r\nwemake_python_styleguide/logic/arguments/function_args.py:126: error: Argument 1 to \"get\" of \"Mapping\" has incompatible type \"Optional[Any]\"; expected \"str\"\r\n```\r\n\r\nSimplier repro:\r\n\r\n```python\r\nfrom typing import Mapping, Any, Optional\r\n\r\nx: Optional[Any]\r\nm: Mapping[str, int]\r\n\r\nm.get(x)\r\n# error: Argument 1 to \"get\" of \"Mapping\" has incompatible type \"Optional[Any]\"; expected \"str\"\r\n```\r\n\r\nSo, what do you think: is this a valid error? Because it will work at runtime with no problem. And since it has `Any` part in it, sometimes it can even be `str`. So, in my app it was working as expected in all cases: if `x` is `str` and exists in `m` - then fine. If not - then just return `None`.\r\n\r\nI am openning it here, because it looks like a typeshed issue, rather than a mypy issue.","author":{"url":"https://github.com/sobolevn","@type":"Person","name":"sobolevn"},"datePublished":"2021-12-16T09:41:35.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/6597/typeshed/issues/6597"}