code: def testUnbounded(self):
      buf = py_metrics.NumpyDeque(
          maxlen=np.inf, dtype=np.float64
      )  # pytype: disable=wrong-arg-types  # numpy-scalars
      for i in range(101):
          buf.add(i)
      self.assertEqual(50, buf.mean())
  
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.metrics import py_metrics
  from tf_agents.trajectories import time_step
  from tf_agents.trajectories import trajectory
  from tf_agents.utils import nest_utils
label_desc: Use image node_id 5 for calling the NumpyDequeTest obj's underlying member method code with example usage: obj.testUnbounded() without return types