code: def _create_multiindex_column(df: pd.DataFrame, right: pd.DataFrame):
      """
      Create a MultiIndex column for conditional_join.
      """
      header = np.empty(df.columns.size, dtype="U4")
      header[:] = "left"
      header = [header]
      columns = [
          df.columns.get_level_values(n)
          for n in range(df.columns.nlevels)
      ]
      header.extend(columns)
      df.columns = pd.MultiIndex.from_arrays(header)
      header = np.empty(right.columns.size, dtype="U5")
      header[:] = "right"
      header = [header]
      columns = [
          right.columns.get_level_values(n)
          for n in range(right.columns.nlevels)
      ]
      header.extend(columns)
      right.columns = pd.MultiIndex.from_arrays(header)
      return df, right
  
imports: from __future__ import annotations
  import operator
  import warnings
  from typing import Any, Hashable, Literal, Optional, Union
  import numpy
  import pandas
  import pandas_flavor
  from pandas.api.types import is_datetime64_dtype, is_dtype_equal, is_extension_array_dtype, is_numeric_dtype, is_timedelta64_dtype
  from pandas.core.reshape.merge import _MergeOperation
  from janitor.functions.utils import _generic_func_cond_join, _JoinOperator, _keep_output, col, greater_than_join_types, less_than_join_types
  from janitor.utils import check, check_column, find_stack_level
label_desc: Use image node_id 11 for calling a global function with example usage: _create_multiindex_column(df, right) and returns: df,  right