docs: def options(self, parser, env):
          """Sets additional command line options."""
          Plugin.options(self, parser, env)
          parser.add_option(
              '--html-file', action='store',
              dest='html_file', metavar="FILE",
              default=env.get('NOSE_HTML_FILE', 'nosetests.html'),
              help="Path to html file to store the report in. "
                   "Default is nosetests.html in the working directory "
                   "[NOSE_HTML_FILE]")