code: def test_mount_gradio_app_with_app_kwargs(self):
      app = FastAPI()
  
      demo = gr.Interface(
          lambda s: f"You said {s}!", "textbox", "textbox"
      ).queue()
  
      app = gr.mount_gradio_app(
          app,
          demo,
          path="/echo",
          app_kwargs={"docs_url": "/docs-custom"},
      )
  
      # Use context manager to trigger start up events
      with TestClient(app) as client:
          assert client.get("/echo/docs-custom").is_success
  
imports: import functools
  import os
  import tempfile
  from contextlib import asynccontextmanager, closing
  from unittest import mock
  import gradio_client
  import numpy
  import pandas
  import pytest
  import starlette.routing
  from fastapi import FastAPI
  from fastapi.testclient import TestClient
  from gradio_client import media_data
  import gradio
  from gradio import Blocks, Button, Interface, Number, Textbox, close_all, routes, wasm_utils
  from gradio.route_utils import FnIndexInferError
label_desc: Use image node_id 18 for calling the TestRoutes obj's underlying member method code with example usage: obj.test_mount_gradio_app_with_app_kwargs() without return types