def top(self) -> T | None:
        """The topmost item on the stack.  If the stack is empty,
        `None` is returned.
        """
        stack = self._storage.get([])

        if len(stack) == 0:
            return None

        return stack[-1]
The topmost item on the stack.  If the stack is empty,
        `None` is returned.
        
src/werkzeug/local.py