code: def order_book(self, group=True, base="btc", quote="usd"):
          
          params = {'group': group}
          url = self._construct_url("order_book/", base, quote)
          return self._get(url, params=params, return_json=True, version=2)
docs: Returns dictionary with "bids" and "asks".
  
          Each is a list of open orders and each order is represented as a list
          of price and amount.