Larry R. Williams explains this strategy in his book "Long-Term secrets to Short-Term trading", it consists of using two 3-period EMAs, one representing the Highs and the other the Lows.
When the price falls below the 3-period Lows EMA we have a long signal.
The trade is closed when the price closes above the 3-period Highs EMA .
UPDATE 06/11/2021: No more Repaint.