code: def __getitem__(self, key):
      if key.startswith("M"):
          return 12
      elif key.startswith("Q"):
          return 4
      elif key.startswith("W"):
          return 52
  
imports: from statsmodels.compat.pandas import deprecate_kwarg
  import os
  import subprocess
  import tempfile
  import re
  from warnings import warn
  import pandas
  from statsmodels.tools.tools import Bunch
  from statsmodels.tools.sm_exceptions import X13NotFoundError, IOWarning, X13Error, X13Warning
label_desc: Use image node_id 1 for calling the _freq_to_period obj's underlying member method code with example usage: obj.__getitem__(key) and returns: int, int, int