code: def testAxis0DefaultCPU(self):
      # tf.parallel_stack is only supported in graph mode.
      with ops.Graph().as_default():
          with test_util.device(use_gpu=False):
              t = [
                  constant_op.constant([1, 2, 3]),
                  constant_op.constant([4, 5, 6]),
              ]
              stacked = self.evaluate(array_ops_stack.stack(t))
              parallel_stacked = self.evaluate(
                  array_ops.parallel_stack(t)
              )
  
          expected = np.array([[1, 2, 3], [4, 5, 6]])
          self.assertAllEqual(stacked, expected)
          self.assertAllEqual(parallel_stacked, expected)
  
imports: import numpy
  from tensorflow.python import tf2
  from tensorflow.python.eager import context
  from tensorflow.python.eager import def_function
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import array_ops_stack
  from tensorflow.python.ops import gen_array_ops
  from tensorflow.python.ops import gradient_checker_v2
  from tensorflow.python.ops import math_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 13 for calling the StackOpTest obj's underlying member method code with example usage: obj.testAxis0DefaultCPU() without return types