Need someone to add 1 data point to already existing code on Tradingview in Pine Script

in tradingview website in the chart drawing tools there is a 'Price and Date Range' where you click drag and drop a square around a group of candle sticks and it totals up the price range and the date range and the percent of price change difference. All i want to do is simply add the total volume in all those very same candlesticks. All data is already in the chart inside the 'volume' bars which share the same exact location ad the candlesticks. I just want to add the accumulated volume data point together and return that number. Thats it!