code: def __call__(self, trajectory_):
      def _add_trajectory(*t):
          self._trajectories.append(
              tf.nest.pack_sequence_as(trajectory_, t)
          )
  
      tf.numpy_function(
          _add_trajectory, tf.nest.flatten(trajectory_), []
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import parameterized
  import numpy
  import tensorflow
  from tf_agents.drivers import test_utils
  from tf_agents.drivers import tf_driver
  from tf_agents.environments import batched_py_environment
  from tf_agents.environments import tf_py_environment
  from tf_agents.trajectories import trajectory
  from tf_agents.utils import nest_utils
  from tf_agents.utils import test_utils
label_desc: Use image node_id 2 for calling the MockReplayBufferObserver obj's underlying member method code with example usage: obj.__call__(trajectory_) without return types