def __getitem__(
        self, key: str | t.SupportsIndex | slice
    ) -> float | tuple[str, float] | list[tuple[str, float]]:
        """Besides index lookup (getting item n) you can also pass it a string
        to get the quality for the item.  If the item is not in the list, the
        returned quality is ``0``.
        """
        if isinstance(key, str):
            return self.quality(key)
        return list.__getitem__(self, key)
Besides index lookup (getting item n) you can also pass it a string
        to get the quality for the item.  If the item is not in the list, the
        returned quality is ``0``.
        
src/werkzeug/datastructures/accept.py