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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def item(self, index: int) -> Optional[Node]: """Return item with the index. If the index is negative number or out of the list, return None. """

        if not isinstance(index, int):
            raise TypeError(
                'Indeces must be integer, not {}'.format(type(index)))
        return self.__nodes[index] if 0 <= index < self.length else None