code: def run():
      """Run command."""
      from mne.commands.utils import get_optparser
  
      parser = get_optparser(__file__)
  
      parser.add_option(
          "-s",
          "--surf",
          dest="surf",
          help="Surface in Freesurfer format",
          metavar="FILE",
      )
      parser.add_option(
          "-f",
          "--fif",
          dest="fif",
          help="FIF file produced",
          metavar="FILE",
      )
      parser.add_option(
          "-i",
          "--id",
          dest="id",
          default=4,
          help=("Surface Id (e.g. 4 for head surface)"),
      )
  
      options, args = parser.parse_args()
  
      if options.surf is None:
          parser.print_help()
          sys.exit(1)
  
      print("Converting %s to BEM FIF file." % options.surf)
      surf = mne.bem._surfaces_to_bem(
          [options.surf], [int(options.id)], sigmas=[1]
      )
      mne.write_bem_surfaces(options.fif, surf)
  
label_desc: Use image node_id 1 for calling a global function with example usage: run() without return types