class_docstr: Deque implementation using a numpy array as a circular buffer.
code: def last(self):
      if not self._len > 0:
          raise RuntimeError("Attempting to access empty NumpyDeque.")
  
      last_index = int(
          (self._start_index + self._len - 1) % self._maxlen
      )
      return self._buffer[last_index]
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import abc
  from typing import Any, Iterable, Optional, Text
  import gin
  import numpy
  import six
  from tf_agents.metrics import py_metric
  from tf_agents.trajectories import trajectory
  from tf_agents.typing import types
  from tf_agents.utils import nest_utils
  from tf_agents.utils import numpy_storage
label_desc: Use image node_id 5 for calling the NumpyDeque obj's underlying member method code with example usage: obj.last() and returns: self