code: def GetVolumeByIndex(self, volume_index):
      
      if not self._is_parsed:
        self._Parse()
        self._is_parsed = True
  
      if volume_index < 0 or volume_index >= len(self._volume_identifiers):
        return None
  
      volume_identifier = self._volume_identifiers[volume_index]
      return self._volumes[volume_identifier]
docs: Retrieves a specific volume based on the index.
  
      Args:
        volume_index (int): index of the volume.
  
      Returns:
        Volume: a volume or None if not available.