code: public static BitfinexOrderBookSymbol fromJSON(final JSONObject jsonObject) {
  		BitfinexCurrencyPair symbol = BitfinexCurrencyPair.fromSymbolString(jsonObject.getString("symbol"));
  		Precision prec = Precision.valueOf(jsonObject.getString("prec"));
  		Frequency freq = null;
  		Integer len = null;
  		if (prec != Precision.R0) {
  			freq = Frequency.valueOf(jsonObject.getString("freq"));
  			len = jsonObject.getInt("len");
  		}
  		return new BitfinexOrderBookSymbol(symbol, prec, freq, len);
  	}
docs: Build from JSON Array
  @param jsonObject
  @return