docs: def _print_split_model(self, path, apps_models):
          """
          Print each model in apps_models into its own file.
          """
          for app, models in apps_models:
              for model in models:
                  model_name = model().title
                  if self._has_extension(path):
                      model_path = re.sub(r'^(.*)[.](\w+)$', r'\1.%s.%s.\2' % (app, model_name), path)
                  else:
                      model_path = '%s.%s.%s.puml' % (path, app, model_name)
                  self._print_single_file(model_path, [(app, [model])])