Scanner for Amibroker, need help

Algos, strategies, code
1

Please help me with the Amibroker AFL
Need a scanner for stocks to trade the next day fulfilling this criteria.

Buy when EMA 15 is above EMA 30 irrelevant of the stock price BUT the important thing here is
William’s %R(3) is below -80(oversold)

Sell when EMA 30 is above EMA 15 irrelevant of the stock price BUT the important thing here is
William’s %R(3) is above -20(overbought)

Finding it difficult to code in Williams %R indicator,
please note this is not a crossover strategy.

Thanks.