code: def _make_name(col_name, sep="_"):
      """Combine elements of `col_name` into a single string, or no-op if
      `col_name` is already a string
      """
      if isinstance(col_name, str):
          return col_name
      return sep.join(name for name in col_name if name != "")
  
imports: from functools import wraps
  from typing import Set
  import numpy
  import pandas
  from dask.dataframe.core import DataFrame, aca, split_out_on_cols
  from dask.dataframe.groupby import DataFrameGroupBy, SeriesGroupBy
  from dask.utils import funcname
  import cudf
  from cudf.utils.nvtx_annotation import _dask_cudf_nvtx_annotate
  from dask_cudf.sorting import _deprecate_shuffle_kwarg
label_desc: Use image node_id 8 for calling a global function with example usage: _make_name(col_name, sep) and returns: sep, col_name