class_docstr: Class responsible for handling input data and extracting metadata into the
  appropriate form
class_docstr_tok: ["Class","responsible","for","handling","input","data","and","extracting","metadata","into","the","appropriate","form"]
code: def _get_names(self, arr):
      if isinstance(arr, DataFrame):
          if isinstance(arr.columns, MultiIndex):
              # Flatten MultiIndexes into "simple" column names
              return [
                  "_".join(level for level in c if level)
                  for c in arr.columns
              ]
          else:
              return list(arr.columns)
      elif isinstance(arr, Series):
          if arr.name:
              return [arr.name]
          else:
              return
      else:
          try:
              return arr.dtype.names
          except AttributeError:
              pass
  
      return None
  
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 17 for calling the ModelData obj's underlying member method code with example usage: obj._get_names(arr) and returns: None, unknown, list, list, arr