code: def test_create_variables(self):
      observation_spec = specs.TensorSpec(
          [1], tf.float32, "observation"
      )
      action_spec = specs.TensorSpec([1], tf.float32, "action")
      input_spec = (observation_spec, action_spec)
      state_spec = tf.TensorSpec([], tf.float32, "state")
      net = MockStateFullNetwork(input_spec, state_spec)
      self.assertFalse(net.built)
      with self.assertRaises(ValueError):
          net.variables  # pylint: disable=pointless-statement
      output_spec = net.create_variables()
  
      self.assertEqual(
          output_spec, tf.TensorSpec([1, 1], dtype=tf.float32)
      )
      self.assertTrue(net.built)
      self.assertLen(net.variables, 2)
      self.assertLen(net.trainable_variables, 1)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import parameterized
  import tensorflow
  import tensorflow_probability
  from tf_agents import specs
  from tf_agents.distributions import utils
  from tf_agents.keras_layers import rnn_wrapper
  from tf_agents.networks import network
  from tf_agents.utils import common
label_desc: Use image node_id 5 for calling the StateFullNetworkTest obj's underlying member method code with example usage: obj.test_create_variables() without return types