Switch to specific chunk

        :param index:

def _useChunk(self, index) -> None:
        """
        Switch to specific chunk

        :param index:
        """

        if self.currentChunk is not None:
            if self.currentChunkIndex == index and \
                    not self.currentChunk.closed:
                return
            self.currentChunk.close()

        self.currentChunk = self._openChunk(index)
        self.currentChunkIndex = index
        self.itemNum = self.currentChunk.numKeys + 1