'Add files to a permanent checkpoint.
:param set save_files: set of filepaths to save
:param str save_notes: notes about changes during the save'

def add_to_checkpoint(self, save_files, save_notes):

    self._check_tempfile_saves(save_files)
    self._add_to_checkpoint_dir(self.config.in_progress_dir, save_files, save_notes)
