docs: def _print_split_app(self, path, apps_models):
          """
          Print each app in apps_models associative list into its own file.
          """
          for app, models in apps_models:
              # Convert dir/file.puml to dir/file.app.puml to print to an app specific file
              if self._has_extension(path):
                  app_path = re.sub(r'^(.*)[.](\w+)$', r'\1.%s.\2' % app, path)
              else:
                  app_path = '%s.%s.puml' % (path, app)
  
              self._print_single_file(app_path, [(app, models)])