code: def test_concrete_function_conversion():
      # testing : https://coremltools.readme.io/docs/tensorflow-2#conversion-from-user-defined-models
  
      import tensorflow as tf
  
      @tf.function(
          input_signature=[tf.TensorSpec(shape=(6,), dtype=tf.float32)]
      )
      def gelu_tanh_activation(x):
          a = np.sqrt(2 / np.pi) * (x + 0.044715 * tf.pow(x, 3))
          y = 0.5 * (1.0 + tf.tanh(a))
          return x * y
  
      conc_func = gelu_tanh_activation.get_concrete_function()
      ct.convert([conc_func])
  
imports: from os import getcwd, chdir
  from shutil import rmtree
  from os.path import exists
  from tempfile import mkdtemp
  import pytest
  import numpy
  import coremltools
  import os
  from coremltools._deps import _HAS_TF_1, _HAS_TF_2, _HAS_TORCH, MSG_TF1_NOT_FOUND, MSG_TF2_NOT_FOUND, MSG_TORCH_NOT_FOUND
label_desc: Use image node_id 8 for calling the TestTensorFlow2ConverterExamples obj's underlying member method code with example usage: obj.test_concrete_function_conversion() and returns: unknown