code: def _get_names(self, arr):
      return arr.design_info.column_names
  
imports: from __future__ import annotations
  from statsmodels.compat.python import lmap
  from functools import reduce
  import numpy
  from pandas import DataFrame, Series, isnull, MultiIndex
  import statsmodels.tools.data
  from statsmodels.tools.decorators import cache_readonly, cache_writable
  from statsmodels.tools.sm_exceptions import MissingDataError
label_desc: Use image node_id 1 for calling the PatsyData obj's underlying member method code with example usage: obj._get_names(arr) and returns: arr