code: def site_name(self, site_name):
          
          if site_name in SITE_LIST:
              self.__site_name = site_name
              self.__site_url = SITE_LIST[site_name]['url']
          else:
              raise PybooruError(
                  "The 'site_name' is not valid, specify a valid 'site_name'.")
docs: Function that sets and checks the site name and set url.
  
          Parameters:
              site_name (str): The site name in 'SITE_LIST', default sites.
  
          Raises:
              PybooruError: When 'site_name' isn't valid.