code: def testConcat(self, left, right):
      self.assertIsInstance(left + right, ph.Placeholder)
  
imports: import os
  from typing import Type, TypeVar
  from absl.testing import parameterized
  import tensorflow
  from tfx.dsl.placeholder import placeholder
  from tfx.proto.orchestration import placeholder_pb2
  from tfx.types import channel_utils
  from tfx.types import standard_artifacts
  from tfx.types.artifact import Artifact
  from tfx.types.artifact import Property
  from tfx.types.artifact import PropertyType
  from tfx.types.channel import Channel
  from google.protobuf import message
  from google.protobuf import text_format
label_desc: Use image node_id 2 for calling the ChannelWrappedPlaceholderTest obj's underlying member method code with example usage: obj.testConcat(left, right) without return types