docs: def setup(self, app):
          """ Setup the plugin from an application. """
          super().setup(app)
  
          if isinstance(self.cfg.template_folders, str):
              self.cfg.template_folders = [self.cfg.template_folders]
  
          self.cfg.template_folders = list(self.cfg.template_folders)
          if not self.cfg.loader:
              self.cfg.loader = FileSystemLoader(
                  self.cfg.template_folders, encoding=self.cfg.encoding)
  
          self.env = jinja2.Environment(
              auto_reload=self.cfg.auto_reload,
              cache_size=self.cfg.cache_size,
              extensions=self.cfg.extensions,
              loader=self.cfg.loader,
          )
          self.env.globals['app'] = app
  
          @self.register
          @jinja2.contextfunction
          def debug(ctx, value=None):
              """ Debug current context to template. """
              return jinja2.filters.do_pprint(value is None and ctx or value)
  
          @self.filter
          def jsonify(obj):
              return dumps(obj, ensure_ascii=False, encode_html_chars=True)