code: def test_unique(self):
      file_path = os.path.join(self.resource_path, "orca/data/csv")
      data_shard = zoo.orca.data.pandas.read_csv(file_path)
      location_list = data_shard["location"].unique()
      assert len(location_list) == 6
  
imports: import os.path
  import shutil
  import pytest
  from unittest import TestCase
  import zoo.orca.data
  import zoo.orca.data.pandas
  from zoo.orca import OrcaContext
  from zoo.orca.data import SharedValue
  from zoo.common.nncontext import *
  from zoo.orca.data import SparkXShards
label_desc: Use image node_id 10 for calling the TestSparkXShards obj's underlying member method code with example usage: obj.test_unique() without return types