code: def test_dayofweek(self):
      self.check_func(lambda x: x.dt.dayofweek)
  
imports: import datetime
  import unittest
  import numpy
  import pandas
  from pyspark import pandas
  from pyspark.testing.pandasutils import PandasOnSparkTestCase
  from pyspark.testing.sqlutils import SQLTestUtils
label_desc: Use image node_id 21 for calling the SeriesDateTimeTestsMixin obj's underlying member method code with example usage: obj.test_dayofweek() without return types