code: def pd_start_date(self):
      return self.pdf1["start_date"]
  
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 2 for calling the SeriesDateTimeTestsMixin obj's underlying member method code with example usage: obj.pd_start_date() and returns: self