code: def AddWarning(self, warning):
      
      self._RaiseIfNotWritable()
  
      self._AddAttributeContainer(
          self._CONTAINER_TYPE_EXTRACTION_WARNING, warning)
docs: Adds an warning.
  
      Args:
        warning (ExtractionWarning): warning.
  
      Raises:
        IOError: when the storage file is closed or read-only.
        OSError: when the storage file is closed or read-only.