code: def _get_period_alias(
      freq: timedelta | BaseOffset | str,
  ) -> str | None:
      freqstr = to_offset(freq, is_period=True).rule_code
  
      return get_period_alias(freqstr)
  
imports: from __future__ import annotations
  import functools
  from typing import TYPE_CHECKING, Any, cast
  import warnings
  import numpy
  from pandas._libs.tslibs import BaseOffset, Period, to_offset
  from pandas._libs.tslibs.dtypes import OFFSET_TO_PERIOD_FREQSTR, FreqGroup
  from pandas.core.dtypes.generic import ABCDatetimeIndex, ABCPeriodIndex, ABCTimedeltaIndex
  from pandas.io.formats.printing import pprint_thing
  from pandas.plotting._matplotlib.converter import TimeSeries_DateFormatter, TimeSeries_DateLocator, TimeSeries_TimedeltaFormatter
  from pandas.tseries.frequencies import get_period_alias, is_subperiod, is_superperiod
label_desc: Use image node_id 8 for calling a global function with example usage: _get_period_alias(freq) and returns: get_period_alias