How to use the gsutil.GsUtil function in gsutil

def main():
  parser = _ParseOptions()
  (options, args) = parser.parse_args()
  # Determine which targets to build. By default we build the "all" target.
  if args:
    print 'only options should be passed to this script'
    parser.print_help()
    return 1

  revision = options.revision
  src_rev = options.srcrev

  gsu = gsutil.GsUtil(running_on_buildbot=False)
  elements = ['DartBuild-linux.gtk.x86_64.zip',
              'DartBuild-linux.gtk.x86.zip',
              'DartBuild-macosx.cocoa.x86_64.zip',
              'DartBuild-macosx.cocoa.x86.zip',
              'DartBuild-win32.win32.x86_64.zip',
              'DartBuild-win32.win32.x86.zip',
              'dart-editor-linux.gtk.x86_64.zip',
              'dart-editor-linux.gtk.x86.zip',
              'dart-editor-macosx.cocoa.x86_64.zip',
              'dart-editor-macosx.cocoa.x86.zip',
              'dart-editor-win32.win32.x86_64.zip',
              'dart-editor-win32.win32.x86.zip']
  os_names = []
  re_filename = re.compile(
      r'^(dart-editor|DartBuild)-(\w.+)\.(\w.+)\.(\w+)\.zip')
  for element in elements:

% (builder_name, EDITOR_REGEXP))

    CHANNEL = match.groupdict()['channel'] or 'be'
    SYSTEM = match.groupdict()['system']
    BUILD_INSTALLER = bool(match.groupdict()['installer'])

    PLUGINS_BUILD = SYSTEM is None
    REVISION = revision

    # Make sure the buildername and the options agree
    assert BUILD_INSTALLER == options.build_installer

    running_on_buildbot = username.startswith('chrome')

    homegsutil = join(DART_PATH, 'third_party', 'gsutil', 'gsutil')
    gsu = gsutil.GsUtil(False, homegsutil,
      running_on_buildbot=running_on_buildbot)

    def build_installer():
      release_type = bot_utils.ReleaseType.SIGNED
      if CHANNEL == 'be':
        # We don't have signed bits on bleeding_edge, so we take the unsigned
        # editor.
        release_type = bot_utils.ReleaseType.RAW
      if SYSTEM == 'win':
        # The windows installer will use unsigned *.exe files to avoid going
        # through two rounds of signing.
        release_type = bot_utils.ReleaseType.RAW

      def editor_location(arch):
        namer = bot_utils.GCSNamer(CHANNEL, release_type)
        editor_path = namer.editor_zipfilepath(REVISION, SYSTEM, arch)