Insert item at the specific index.
        :param index: Index where to insert the item.
        :param item: Item to insert.

def insert(self, index, item):
        # type: (int, Any) -> None
        """
        Insert item at the specific index.
        :param index: Index where to insert the item.
        :param item: Item to insert.
        """
        return list.insert(self, index, self.ref(item))