code: def testCreatePlaceholderFromTuple(self):
      self.skipIfExecutingEagerly()
      specs = (
          tensor_spec.TensorSpec(
              shape=(), dtype=tf.float32, name="act_prob"
          ),
          tensor_spec.TensorSpec(
              shape=(), dtype=tf.float32, name="value_pred"
          ),
      )
      ph = tensor_spec.to_nest_placeholder(specs)
      self.assertEqual(2, len(ph))
      self.assertEqual(ph[0].name, "act_prob:0")
      self.assertEqual(ph[0].dtype, tf.float32)
      self.assertEqual(ph[0].shape, tf.TensorShape([]))
      self.assertEqual(ph[1].name, "value_pred:0")
      self.assertEqual(ph[1].dtype, tf.float32)
      self.assertEqual(ph[1].shape, tf.TensorShape([]))
  
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.specs import array_spec
  from tf_agents.specs import tensor_spec
  from tf_agents.trajectories import time_step
label_desc: Use image node_id 2 for calling the ToPlaceholderTest obj's underlying member method code with example usage: obj.testCreatePlaceholderFromTuple() without return types