code: def test_loc_datetime_no_freq(self):
      datetime_index = pd.date_range(
          "2016-01-01", "2016-01-31", freq="12h"
      )
      datetime_index.freq = None  # FORGET FREQUENCY
      pdf = pd.DataFrame(
          {"num": range(len(datetime_index))}, index=datetime_index
      )
      psdf = ps.from_pandas(pdf)
  
      slice_ = slice("2016-01-03", "2016-01-05")
      result = psdf.loc[slice_, :]
      expected = pdf.loc[slice_, :]
      self.assert_eq(result, expected)
  
imports: 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 12 for calling the IndexingLocMixin obj's underlying member method code with example usage: obj.test_loc_datetime_no_freq() without return types