code: def _get_index_map(
      sdf: PySparkDataFrame,
      index_col: Optional[Union[str, List[str]]] = None,
  ) -> Tuple[Optional[List[PySparkColumn]], Optional[List[Label]]]:
      index_spark_columns: Optional[List[PySparkColumn]]
      index_names: Optional[List[Label]]
      if index_col is not None:
          if isinstance(index_col, str):
              index_col = [index_col]
          sdf_columns = set(sdf.columns)
          for col in index_col:
              if col not in sdf_columns:
                  raise KeyError(col)
          index_spark_columns = [
              scol_for(sdf, col) for col in index_col
          ]
          index_names = [(col,) for col in index_col]
      else:
          index_spark_columns = None
          index_names = None
  
      return index_spark_columns, index_names
  
imports: from typing import Any, Callable, Dict, List, Optional, Set, Sized, Tuple, Type, Union, cast, no_type_check
  from collections.abc import Iterable
  from datetime import tzinfo
  from functools import reduce
  from io import BytesIO
  import json
  import warnings
  import numpy
  import pandas
  from pandas.api.types import is_datetime64_dtype, is_list_like
  from pandas.tseries.offsets import DateOffset
  import pyarrow
  import pyarrow.parquet
  from pyspark.sql import functions, Column
  from pyspark.sql.functions import pandas_udf
  from pyspark.sql.types import ByteType, ShortType, IntegerType, LongType, FloatType, DoubleType, BooleanType, TimestampType, TimestampNTZType, DecimalType, StringType, DateType, StructType, DataType
  from pyspark.sql.dataframe import DataFrame
  from pyspark import pandas
  from pyspark.pandas._typing import Axis, Dtype, Label, Name
  from pyspark.pandas.base import IndexOpsMixin
  from pyspark.pandas.utils import align_diff_frames, default_session, is_name_like_tuple, is_name_like_value, name_like_string, same_anchor, scol_for, validate_axis, log_advice
  from pyspark.pandas.frame import DataFrame, _reduce_spark_multi
  from pyspark.pandas.internal import InternalFrame, DEFAULT_SERIES_NAME, HIDDEN_COLUMNS, SPARK_INDEX_NAME_FORMAT
  from pyspark.pandas.series import Series, first_series
  from pyspark.pandas.spark.utils import as_nullable_spark_type, force_decimal_precision_scale
  from pyspark.pandas.indexes import Index, DatetimeIndex, TimedeltaIndex
  from pyspark.pandas.indexes.multi import MultiIndex
  from pyspark.sql.utils import get_column_class
label_desc: Use image node_id 29 for calling a global function with example usage: _get_index_map(sdf, index_col) and returns: index_spark_columns,  index_names