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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"None-ness falsely assumed in loop","articleBody":"**Bug Report**\r\n\r\nAfter `foo = None`, mypy thinks that `foo` will always be `None`, even if a loop can jump between the assignment and the use of `foo`.\r\n\r\n**To Reproduce**\r\n\r\n```python\r\ndef main() -\u003e None:\r\n    gonna_select = None\r\n    while True:\r\n        if gonna_select is not None:\r\n            print(1 + \"lol\")\r\n        gonna_select = \"lol\"\r\n```\r\n\r\n**Expected Behavior**\r\n\r\nerror from `1 + \"lol\"`\r\n\r\n**Actual Behavior**\r\n\r\nno error\r\n\r\n**Your Environment**\r\n\r\n- Mypy version used: 0.910\r\n- Mypy command-line flags: none\r\n- Mypy configuration options from `mypy.ini` (and other config files): none\r\n- Python version used: 3.7","author":{"url":"https://github.com/Akuli","@type":"Person","name":"Akuli"},"datePublished":"2021-11-01T22:14:14.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/11430/mypy/issues/11430"}