Specially for @AlexMayorov:
1) Buy when indicator crosses the zero line upside
2) Sell when indicator crosses the zero line downside
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.
A list of Paid indicators: