code: def test_infer_freq_tz_transition_custom():
      index = date_range(
          "2013-11-03", periods=5, freq="3h"
      ).tz_localize("America/Chicago")
      assert index.inferred_freq is None
  
imports: from datetime import datetime, timedelta
  import numpy
  import pytest
  from pandas._libs.tslibs.ccalendar import DAYS, MONTHS
  from pandas._libs.tslibs.offsets import _get_offset
  from pandas._libs.tslibs.period import INVALID_FREQ_ERR_MSG
  from pandas.compat import is_platform_windows
  from pandas import DatetimeIndex, Index, RangeIndex, Series, Timestamp, date_range, period_range
  import pandas._testing
  from pandas.core.arrays import DatetimeArray, TimedeltaArray
  from pandas.core.tools.datetimes import to_datetime
  from pandas.tseries import frequencies, offsets
label_desc: Use image node_id 20 for calling a global function with example usage: test_infer_freq_tz_transition_custom() without return types