code: def testRefType(self):
      with test_util.use_gpu():
          p1 = np.random.rand(4, 4).astype("f")
          p2 = np.random.rand(4, 4).astype("f")
          v1 = variables.Variable(p1)
          v2 = variables.Variable(p2)
          c = array_ops.concat([v1, v2], 0)
          self.evaluate(variables.global_variables_initializer())
          result = self.evaluate(c)
  
      self.assertEqual(result.shape, c.get_shape())
      self.assertAllEqual(result[:4, :], p1)
      self.assertAllEqual(result[4:, :], p2)
  
imports: import numpy
  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_impl
  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 gen_array_ops
  from tensorflow.python.ops import gradient_checker
  from tensorflow.python.ops import gradients_impl
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import nn_ops
  from tensorflow.python.ops import variables
  from tensorflow.python.platform import test
label_desc: Use image node_id 8 for calling the ConcatOpTest obj's underlying member method code with example usage: obj.testRefType() without return types