code: def test_all_variants_have_configs(self):
      for variant in grpc_util.ChannelCredsType.__members__.values():
          (creds, options) = variant.channel_config()
          self.assertIsInstance(creds, grpc.ChannelCredentials)
          self.assertIsInstance(options, list)
  
imports: import contextlib
  import hashlib
  import threading
  import time
  from concurrent import futures
  import grpc
  from tensorboard.util import grpc_util
  from tensorboard.util import grpc_util_test_pb2
  from tensorboard.util import grpc_util_test_pb2_grpc
  from tensorboard.util import test_util
  from tensorboard import test
  from tensorboard import version
label_desc: Use image node_id 1 for calling the ChannelCredsTypeTest obj's underlying member method code with example usage: obj.test_all_variants_have_configs() without return types