code: def test_2d_loaders(self):
      with self.assertRaisesRegexp(ValueError, ""):
          self.load_2d_image("test")
      self.load_2d_image()
      for _loader in image_loader.AVAILABLE_LOADERS.keys():
          print("testing {}".format(_loader))
          if _loader == "nibabel":
              continue  # skip nibabel for 2d image
          if _loader == "dummy":
              continue  # skip the toy example
          self.load_2d_image(_loader)
  
file_path: NiftyNet/tests/image_loader_test.py
imports: from __future__ import absolute_import, print_function
  import os
  import numpy
  import tensorflow
  import niftynet.io.image_loader
  from tests.niftynet_testcase import NiftyNetTestCase
label_desc: Use image node_id 4 for calling the ImageLoaderTest obj's underlying member method code with example usage: obj.test_2d_loaders() without return types