code: def test_request_get_headers(self):
      def identity(name, request: gr.Request):
          assert isinstance(request.headers["user-agent"], str)
          assert isinstance(request.headers.items(), list)
          assert isinstance(request.headers.keys(), list)
          assert isinstance(request.headers.values(), list)
          assert isinstance(dict(request.headers), dict)
          user_agent = request.headers["user-agent"]
          assert "testclient" in user_agent
          return name
  
      app, _, _ = gr.Interface(identity, "textbox", "textbox").launch(
          prevent_thread_lock=True,
      )
      client = TestClient(app)
  
      response = client.post("/api/predict/", json={"data": ["test"]})
      assert response.status_code == 200
      output = dict(response.json())
      assert output["data"] == ["test"]
  
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 4 for calling the TestPassingRequest obj's underlying member method code with example usage: obj.test_request_get_headers() and returns: name