def save_files(self, files, branch_name, commit_message=None):
        """Save a multiple files and advances the specified branch head.

        If the branch does not exist yet, it will be created.
        """
        files_info = {}
        for path, data in files.items():
            if not isinstance(data, (list, tuple)):
                data = (data, CHANGE_MODIFY)
            files_info[path] = data
        self._perform_file_operation(
            branch_name, self._save_files, files_info, commit_message)
Save a multiple files and advances the specified branch head.

        If the branch does not exist yet, it will be created.
        
portia_server/storage/repoman.py