code: def test_default_flagging_callback(self):
      with tempfile.TemporaryDirectory() as tmpdirname:
          io = gr.Interface(
              lambda x: x, "text", "text", flagging_dir=tmpdirname
          )
          io.launch(prevent_thread_lock=True)
          row_count = io.flagging_callback.flag(["test", "test"])
          assert row_count == 1  # 2 rows written including header
          row_count = io.flagging_callback.flag(["test", "test"])
          assert row_count == 2  # 3 rows written including header
      io.close()
  
imports: import os
  import tempfile
  from unittest.mock import MagicMock, patch
  import pytest
  import gradio
  from gradio import flagging
label_desc: Use image node_id 1 for calling the TestDefaultFlagging obj's underlying member method code with example usage: obj.test_default_flagging_callback() without return types