The indicator shall allow users to "analyse" a recent historical candle to detect whether it was a swing point. This will work by inputting a number to select which historical candle you want to check. The indicator will then check all candles after it until the current candle. It shall also check the same amount of candles before it. If the candle analysed has the lowest low or highest high in the complete range, then we know it was a swing point.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.