code: def _is_sub(f1: str, f2: str) -> bool:
      return (f1.startswith("W") and is_subperiod("D", f2)) or (
          f2.startswith("W") and is_subperiod(f1, "D")
      )
  
imports: from __future__ import annotations
  from datetime import timedelta
  import functools
  from typing import TYPE_CHECKING, cast
  import numpy
  from pandas._libs.tslibs import BaseOffset, Period, to_offset
  from pandas._libs.tslibs.dtypes import 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 2 for calling a global function with example usage: _is_sub(f1, f2) and returns: unknown