code: def _a_numpy(self):
      a_for_one_arm = 1.0 + 4.0 * np.eye(
          self._encoding_dim, dtype=np.float32
      )
      return [a_for_one_arm] * self._num_actions
  
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.bandits.networks import global_and_arm_feature_network
  from tf_agents.bandits.policies import neural_linucb_policy
  from tf_agents.bandits.specs import utils
  from tf_agents.networks import network
  from tf_agents.specs import tensor_spec
  from tf_agents.trajectories import time_step
  from tf_agents.utils import common
  from tf_agents.utils import test_utils
label_desc: Use image node_id 3 for calling the NeuralLinUCBPolicyTest obj's underlying member method code with example usage: obj._a_numpy() and returns: unknown