def get_scraperclasses():
    """Find all comic scraper classes in the plugins directory.
    The result is cached.
    @return: list of Scraper classes
    @rtype: list of Scraper
    """
    global _scraperclasses
    if _scraperclasses is None:
        out.debug(u"Loading comic modules...")
        modules = loader.get_modules('plugins')
        plugins = loader.get_plugins(modules, Scraper)
        _scraperclasses = list(plugins)
        check_scrapers()
        out.debug(u"... %d modules loaded." % len(_scraperclasses))
    return _scraperclasses
Find all comic scraper classes in the plugins directory.
    The result is cached.
    @return: list of Scraper classes
    @rtype: list of Scraper