code: def on_mismatch(self, pair):
          
          remote_entry = pair.remote
          if self.options.get("delete_unmatched") and remote_entry:
              self._log_action("delete", "unmatched", ">", remote_entry)
              if remote_entry.is_dir():
                  self._remove_dir(remote_entry)
              else:
                  self._remove_file(remote_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.