code: def test_specify_bits(self, tmp_path):
      im = hopper("P")
  
      out = str(tmp_path / "temp.png")
      im.save(out, bits=4)
  
      with Image.open(out) as reloaded:
          assert len(reloaded.png.im_palette[1]) == 48
  
imports: from __future__ import annotations
  import re
  import sys
  import warnings
  import zlib
  from io import BytesIO
  import pytest
  from PIL import Image, ImageFile, PngImagePlugin, features
  from .helper import PillowLeakTestCase, assert_image, assert_image_equal, assert_image_equal_tofile, hopper, is_win32, mark_if_feature_version, skip_unless_feature
label_desc: Use image node_id 43 for calling the TestFilePng obj's underlying member method code with example usage: obj.test_specify_bits(tmp_path) without return types