code: def ap(helplist, format_, sep=", "):
      """Little helper to enforce consistency"""
      if helplist == "-":
          return helplist
      ls = [format_ % x for x in helplist]
      return sep.join(ls)
  
file_path: nibabel/nibabel/cmdline/utils.py
imports: import re
  from io import StringIO
  from math import ceil
  import numpy
label_desc: Use image node_id 4 for calling a global function with example usage: ap(helplist, format_, sep) and returns: sep, helplist