code: def GetAttributeContainerByIndex(self, index):
      
      if index < 0:
        raise IndexError(
            'Unsupported negative index value: {0:d}.'.format(index))
  
      if index < len(self._list):
        return self._list[index]
  
      return None
docs: Retrieves a specific serialized attribute container from the list.
  
      Args:
        index (int): attribute container index.
  
      Returns:
        bytes: serialized attribute container data or None if not available.
  
      Raises:
        IndexError: if the index is less than zero.