code: def test_extend(self):
      d = tf_metrics.TFDeque(3, tf.int32, shape=(2,))
      self.evaluate(tf.compat.v1.global_variables_initializer())
  
      d.extend([[1, 1], [2, 2], [3, 3], [4, 4]])
      self.evaluate_last_func_if_graph_mode()
  
      self.assertAllEqual(
          [[4, 4], [2, 2], [3, 3]], self.evaluate(d.data)
      )
      self.assertAllEqual([3, 3], self.evaluate(d.mean()))
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import parameterized
  import tensorflow
  from tf_agents.metrics import tf_metrics
  from tf_agents.specs import tensor_spec
  from tf_agents.trajectories import trajectory
  from tensorflow.python.eager import context
label_desc: Use image node_id 9 for calling the TFShapedDequeTest obj's underlying member method code with example usage: obj.test_extend() without return types