code: def test_string_join(self):
      pser = pd.Series([["a", "b", "c"], ["xx", "yy", "zz"]])
      self.check_func_on_series(lambda x: x.str.join("-"), pser)
      self.check_func(lambda x: x.str.join("-"))
  
imports: import pandas
  import numpy
  import re
  from pyspark import pandas
  from pyspark.testing.pandasutils import PandasOnSparkTestCase
  from pyspark.testing.sqlutils import SQLTestUtils
label_desc: Use image node_id 11 for calling the SeriesStringOpsAdvMixin obj's underlying member method code with example usage: obj.test_string_join() without return types