code: def testStringNdArrayRetrieval(self):
      metadata = projector_plugin.EmbeddingMetadata(2)
      metadata.add_column("Labels", np.array(["a", "b"]))
      self.assertEqual(
          metadata.name_to_values["Labels"].tolist(), ["a", "b"]
      )
  
imports: import gzip
  import io
  import json
  import os
  import numpy
  import tensorflow
  import unittest
  from werkzeug import test
  from werkzeug import wrappers
  from google.protobuf import text_format
  from tensorboard.backend import application
  from tensorboard.backend.event_processing import data_provider
  from tensorboard.backend.event_processing import plugin_event_multiplexer
  from tensorboard.compat.proto import event_pb2
  from tensorboard.compat.proto import summary_pb2
  from tensorboard.compat import tf
  from tensorboard.plugins import base_plugin
  from tensorboard.plugins.projector import projector_config_pb2
  from tensorboard.plugins.projector import projector_plugin
  from tensorboard.util import test_util
label_desc: Use image node_id 8 for calling the MetadataColumnsTest obj's underlying member method code with example usage: obj.testStringNdArrayRetrieval() without return types