Syntax error at input '(' on function isEngulfing(open, close) - syntax-error

Question

In summary, the script that you want me to create will alert me when the minimum or maximum of the Asian session is manipulated, depending on the selected bias (bullish or bearish), and when a Shift Candle is formed by an Engulfing with POC above or below the previous candle and volume that exceeds the 20-period moving average of the TradingView Volume indicator.
This is the code:
// Variabili
bias = input(title="Enter bias (Bullish or Bearish)", type=string)
// Funzione per identificare l'Engulfing
function isEngulfing(open, close) return (open \> close\[1\] and close \> open\[1\]) or (open \< close\[1\] and close \< open\[1\])
// Calcoliamo il POC della candela corrente
poc = ((high + low + close) / 3)
// Calcoliamo il POC della candela precedente
poc_prev = ((high\[1\] + low\[1\] + close\[1\]) / 3)
// Funzione per verificare se il volume della candela Engulfing tocca la media mobile a 20 periodi dell'indicatore Volume function checkVolume(volume) return volume \>= sma(volume, 20)
// Funzione ShiftCandle
function ShiftCandle() if bias == "Bullish" if isEngulfing(open, close) and low \<= asian_range.l and checkVolume(volume) and poc \> poc_prev alertcondition(title="Shift Candle Bullish", message="Shift Candle Bullish detected") else if bias == "Bearish" if isEngulfing(open, close) and high \>= asian_range.h and checkVolume(volume) and poc \< poc_prev alertcondition(title="Shift Candle Bearish", message="Shift Candle Bearish detected")
ShiftCandle()
Tradingview compiler show me this error:
Syntax error at input '(' on function isEngulfing**(**open, close)
Can someone help me?
Thanks
Luca
I wish the program would do what I wrote in the initial part before but I just can't solve this problem.
Here are two examples:
Example: 1 - The user selects the bias from the keyboard: bullish 2 - The script alerts the user when the minimum of the Asian session is manipulated 3 - The script alerts the user when the Shift Candle is formed (in this case, the Shift Candle will be formed by a bullish Engulfing, POC of the Engulfing candle higher than the previous candle, the volume of the bullish Engulfing candle will have exceeded the 20-period MA of the TradingView Volume indicator)
Example: 2 - The user selects the bias from the keyboard: bearish 2 - The script alerts the user when the maximum of the Asian session is manipulated 3 - The script alerts the user when the Shift Candle is formed (in this case, the Shift Candle will be formed by a bearish Engulfing, POC of the Engulfing candle lower than the previous candle, the volume of the bearish Engulfing candle will have exceeded the 20-period MA of the TradingView Volume indicator)