code: def _setup_source_and_destination(self):
          
          try:
              self.source = self.config.source.crashstorage_class(
                  self.config.source,
                  quit_check_callback=self.quit_check
              )
          except Exception:
              self.config.logger.critical(
                  'Error in creating crash source',
                  exc_info=True
              )
              raise
          try:
              self.destination = self.config.destination.crashstorage_class(
                  self.config.destination,
                  quit_check_callback=self.quit_check
              )
          except Exception:
              self.config.logger.critical(
                  'Error in creating crash destination',
                  exc_info=True
              )
              raise
docs: instantiate the classes that implement the source and destination
          crash storage systems.