code: def on_mismatch(self, pair):
          
          local_entry = pair.local
          if self.options.get("delete_unmatched") and local_entry:
              self._log_action("delete", "unmatched", "<", local_entry)
              if local_entry.is_dir():
                  self._remove_dir(local_entry)
              else:
                  self._remove_file(local_entry)
          else:
              self._log_action("skip", "unmatched", "-", pair.any_entry, min_level=4)
docs: Called for pairs that don't match `match` and `exclude` filters.
  
          If --delete-unmatched is on, remove the remote resource.