code: def _get_key_location(self, key) -> (int, int):
          
          key = int(key)
          if key == 0:
              return 1, 0
          remainder = key % self.chunkSize
          addend = ChunkedFileStore.firstChunkIndex
          chunk_no = key - remainder + addend if remainder \
              else key - self.chunkSize + addend
          offset = remainder or self.chunkSize
          return chunk_no, offset
docs: Return chunk no and 1-based offset of key
          :param key:
          :return: