code: def test_pickle_dont_infer_freq(self):
      # GH#11002
      # don't infer freq
      idx = date_range("1750-1-1", "2050-1-1", freq="7D")
      idx_p = tm.round_trip_pickle(idx)
      tm.assert_index_equal(idx, idx_p)
  
file_path: pandas/pandas/tests/indexes/datetimes/test_pickle.py
imports: import pytest
  from pandas import NaT, date_range, to_datetime
  import pandas._testing
label_desc: Use image node_id 2 for calling the TestPickle obj's underlying member method code with example usage: obj.test_pickle_dont_infer_freq() without return types