code: def process_data(self, file_info):
          
          if self._is_already_processed(file_info):
              self.log.debug("Content file already processed '%s'", str(file_info))
              self.fire(events.FilteredFile(file_info))
              self.fire(events.FileInfoAlreadyProcessed(file_info))
          else:
              return file_info
          return None
docs: expects FileInfo