filter with None as function

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Accepted Answer

When you pass `None` as the function to `filter()`, it keeps only truthy elements. The falsy values here are 0, `''`, `None`, `[]`, and `False` - all dropped. The truthy values are 1, `'hello'`, and `[1, 2]`. A non-empty list like `[1, 2]` is truthy even though `[]` is falsy. This is a handy one-liner for stripping empty or missing values from a collection.