docstr: Check subclass conversion behavior
code: def test_subclass_conversion(self):
      """Check subclass conversion behavior"""
      x = np.array([-1, 1])
      for dtype in TestOutputPreprocessing.float_dtype_list:
          x = x.astype(dtype)
          y = processing_utils._convert(x, np.floating)
          assert y.dtype == x.dtype
  
imports: import os
  import shutil
  import tempfile
  from copy import deepcopy
  from pathlib import Path
  from unittest.mock import patch
  import ffmpy
  import numpy
  import pytest
  from gradio_client import media_data
  from PIL import Image, ImageCms
  from gradio import processing_utils, utils
label_desc: Use image node_id 2 for calling the TestOutputPreprocessing obj's underlying member method code with example usage: obj.test_subclass_conversion() without return types