code: def test_read_image_mutable(self):
      if self.backend == "cv2" and not _cv2_available:
          return
  
      with chainer.using_config("cv_read_image_backend", self.backend):
          img = read_image(
              self.file, dtype=self.dtype, alpha=self.alpha
          )
      img[:] = 0
      np.testing.assert_equal(img, 0)
  
imports: import numpy
  import tempfile
  import unittest
  from PIL import Image
  import chainer
  from chainer import testing
  from chainercv.utils import read_image
  from chainercv.utils import write_image
label_desc: Use image node_id 4 for calling the TestReadImage obj's underlying member method code with example usage: obj.test_read_image_mutable() without return types