code: def run():
      """Run command."""
      from mne.commands.utils import _add_verbose_flag, get_optparser
  
      parser = get_optparser(__file__)
  
      parser.add_option(
          "-s",
          "--subject",
          dest="subject",
          help="Subject name (required)",
          default=None,
      )
      parser.add_option(
          "-d",
          "--subjects-dir",
          dest="subjects_dir",
          help="Subjects directory",
          default=None,
      )
      parser.add_option(
          "-o",
          "--overwrite",
          dest="overwrite",
          help="Write over existing files",
          action="store_true",
      )
      parser.add_option(
          "-v",
          "--volume",
          dest="volume",
          help="Defaults to T1",
          default="T1",
      )
      parser.add_option(
          "-a",
          "--atlas",
          dest="atlas",
          help="Specify the --atlas option for mri_watershed",
          default=False,
          action="store_true",
      )
      parser.add_option(
          "-g",
          "--gcaatlas",
          dest="gcaatlas",
          help="Specify the --brain_atlas option for " "mri_watershed",
          default=False,
          action="store_true",
      )
      parser.add_option(
          "-p",
          "--preflood",
          dest="preflood",
          help="Change the preflood height",
          default=None,
      )
      parser.add_option(
          "--copy",
          dest="copy",
          help="Use copies instead of symlinks for surfaces",
          action="store_true",
      )
      parser.add_option(
          "-t",
          "--T1",
          dest="T1",
          help="Whether or not to pass the -T1 flag "
          "(can be true, false, 0, or 1). "
          "By default it takes the same value as gcaatlas.",
          default=None,
      )
      parser.add_option(
          "-b",
          "--brainmask",
          dest="brainmask",
          help="The filename for the brainmask output file "
          "relative to the "
          "$SUBJECTS_DIR/$SUBJECT/bem/watershed/ directory.",
          default="ws",
      )
      _add_verbose_flag(parser)
  
      options, args = parser.parse_args()
  
      if options.subject is None:
          parser.print_help()
          sys.exit(1)
  
      subject = options.subject
      subjects_dir = options.subjects_dir
      overwrite = options.overwrite
      volume = options.volume
      atlas = options.atlas
      gcaatlas = options.gcaatlas
      preflood = options.preflood
      copy = options.copy
      brainmask = options.brainmask
      T1 = options.T1
      if T1 is not None:
          T1 = T1.lower()
          _check_option("--T1", T1, ("true", "false", "0", "1"))
          T1 = T1 in ("true", "1")
      verbose = options.verbose
  
      make_watershed_bem(
          subject=subject,
          subjects_dir=subjects_dir,
          overwrite=overwrite,
          volume=volume,
          atlas=atlas,
          gcaatlas=gcaatlas,
          preflood=preflood,
          copy=copy,
          T1=T1,
          brainmask=brainmask,
          verbose=verbose,
      )
  
imports: import sys
  import mne
  from mne.bem import make_watershed_bem
  from mne.utils import _check_option
label_desc: Use image node_id 1 for calling a global function with example usage: run() without return types