code: def patsy_categorical_term(
      term, levels=None, coding=None, quote=True
  ):
      """Returns categorical term for patsy.
          Optionally specify levels, coding, and quote the term
      :param term: str
          name of the categorical variable
      :param levels: list(str) or None
          levels for the categorical variable
      :param coding: str
          A valid coding. E.g. Treatment, Sum, Diff, Poly
          https://patsy.readthedocs.io/en/latest/API-reference.html#handling-categorical-data
      :param quote: bool
          whether to quote the term. Useful if there is a space or "." in the term
      :return: str
          categorical factor for patsy model formula
      """
      if quote:
          term = f"Q('{term}')"
      # constructs the string for the patsy model term
      string = f"C({term}"
      if coding is not None:
          string += f", {coding}"
      if levels is not None:
          string += f", levels={levels}"
      string += ")"
      return string
  
file_path: greykite/greykite/algo/forecast/silverkite/forecast_simple_silverkite_helper.py
imports: import warnings
  import pandas
  from greykite.common import constants
  from greykite.common.constants import EVENT_DF_DATE_COL
  from greykite.common.constants import EVENT_DF_LABEL_COL
  from greykite.common.constants import EVENT_INDICATOR
  from greykite.common.features.timeseries_features import add_event_window_multi
  from greykite.common.features.timeseries_features import get_fourier_col_name
  from greykite.common.features.timeseries_features import get_holidays
  from greykite.common.python_utils import split_offset_str
label_desc: Use image node_id 5 for calling a global function with example usage: patsy_categorical_term(term, levels, coding, quote) and returns: string