text: class AbsDatabase(object):
  
      def add_proxy(self, proxy):
          raise NotImplementedError
  
      def get_all_proxies(self):
          raise NotImplementedError
  
      def get_unknown_anonymity_proxies(self):
          raise NotImplementedError
  
      def increase_reliability(self, url):
          raise NotImplementedError
  
      def reduce_reliability(self, url):
          raise NotImplementedError
  
      def update_anonymity(self, url, value):
          raise NotImplementedError
  
      def remove(self, key):
          raise NotImplementedError
  
      def init_db(self):
          return
  