code: public CoinbasePrice getCoinbaseSellPrice(BigDecimal quantity, String currency)
        throws IOException {
  
      return coinbase.getSellPrice(quantity, currency);
    }
docs: Unauthenticated resource that tells you the total amount you can get if you sell some quantity
  Bitcoin.
  
  @param quantity The quantity of Bitcoin you would like to sell (default is 1 if null).
  @param currency Default is USD. Right now this is the only value allowed.
  @return The price in the desired {@code currency} to sell the given {@code quantity} BTC.
  @throws IOException
  @see <a
  href="https://coinbase.com/api/doc/1.0/prices/sell.html">coinbase.com/api/doc/1.0/prices/sell.html</a>