code: def _maybe_coerce_freq(code) -> str:
      """we might need to coerce a code to a rule_code
      and uppercase it
  
      Parameters
      ----------
      source : str or DateOffset
          Frequency converting from
  
      Returns
      -------
      str
      """
      assert code is not None
      if isinstance(code, DateOffset):
          code = freq_to_period_freqstr(1, code.name)
      if code in {"h", "min", "s", "ms", "us", "ns"}:
          return code
      else:
          return code.upper()
  
imports: from __future__ import annotations
  from typing import TYPE_CHECKING
  import numpy
  from pandas._libs import lib
  from pandas._libs.algos import unique_deltas
  from pandas._libs.tslibs import Timestamp, get_unit_from_dtype, periods_per_day, tz_convert_from_utc
  from pandas._libs.tslibs.ccalendar import DAYS, MONTH_ALIASES, MONTH_NUMBERS, MONTHS, int_to_weekday
  from pandas._libs.tslibs.dtypes import OFFSET_TO_PERIOD_FREQSTR, freq_to_period_freqstr
  from pandas._libs.tslibs.fields import build_field_sarray, month_position_check
  from pandas._libs.tslibs.offsets import DateOffset, Day, to_offset
  from pandas._libs.tslibs.parsing import get_rule_month
  from pandas.util._decorators import cache_readonly
  from pandas.core.dtypes.common import is_numeric_dtype
  from pandas.core.dtypes.dtypes import DatetimeTZDtype, PeriodDtype
  from pandas.core.dtypes.generic import ABCIndex, ABCSeries
  from pandas.core.algorithms import unique
label_desc: Use image node_id 7 for calling a global function with example usage: _maybe_coerce_freq(code) and returns: code, code