code: def check_scrapers():
      
      d = {}
      for scraperclass in _scraperclasses:
          name = scraperclass.getName().lower()
          if name in d:
              name1 = scraperclass.getName()
              name2 = d[name].getName()
              raise ValueError('duplicate scrapers %s and %s found' % (name1, name2))
          d[name] = scraperclass
docs: Check for duplicate scraper class names.