docs: def add_swagger_api_route(app, target_route, swagger_json_route):
      """
      mount a swagger statics page.
  
      app: the flask app object
      target_route: the path to mount the statics page.
      swagger_json_route: the path where the swagger json definitions is
          expected to be.
      """
      static_root = get_swagger_static_root()
      swagger_body = generate_swagger_html(
          STATIC_ROOT, swagger_json_route
      ).encode("utf-8")
  
      def swagger_ui():
          return Response(swagger_body, content_type="text/html")
  
      blueprint = Blueprint('swagger', __name__,
                            static_url_path=STATIC_ROOT,
                            static_folder=static_root)
      app.route(target_route)(swagger_ui)
      app.register_blueprint(blueprint)