code: def get_2d_input(self):
      input_shape = (2, 16, 16, 8)
      x = tf.ones(input_shape)
      return x
  
file_path: NiftyNet/tests/gn_test.py
imports: from __future__ import absolute_import, print_function
  import tensorflow
  from tensorflow.contrib.layers.python.layers import regularizers
  from niftynet.layer.gn import GNLayer
  from tests.niftynet_testcase import NiftyNetTestCase
label_desc: Use image node_id 2 for calling the GNTest obj's underlying member method code with example usage: obj.get_2d_input() and returns: x