Note: Setting higher values of upper and lower deviation may result in error if the price never breaks the channel and the script references too many bars than supported.
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.