text: from exchanges.base import Exchange
  
  
  class Bitfinex(Exchange):
  
      TICKER_URL = 'https://api.bitfinex.com/v1/pubticker/btcusd'
  
      @classmethod
      def _current_price_extractor(cls, data):
          return data.get('last_price')
  
      @classmethod
      def _current_bid_extractor(cls, data):
          return data.get('bid')
  
      @classmethod
      def _current_ask_extractor(cls, data):
          return data.get('ask')
  