Buy sell conditions and alerts when it is above or below 0

Please see below the indicator. It is an oscillator that shows the time segmented volume. I would like to add alerts or alertcondition on it. Buy signal when the bar is above 0, and sell signal when the bar is below 0. I couldn't figure out how to do it.

Thanks for your help

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//      CREDITS: http://quant.stackexchange.com/questions/2816/how-to-calculate-time-segmented-volume

//@version=5
indicator('Time Segmented Volume', shorttitle='TSV', overlay=false)

l = input(defval=13, title='TSV Length')


//t = sum(close>close[1]?volume*close-close[1]:close<close[1]?(volume*-1)*close-close:0,l)
// previous line is non sensical. The correct version follows
t = math.sum(close > close[1] ? volume * (close - close[1]) : close < close[1] ? volume * (close - close[1]) : 0, l)

SwapColor = t > 0 ? color.green : color.red

plot(series=t, title='TSV Histogram', color=SwapColor, style=plot.style_histogram, histbase=0, linewidth=1)

Ok. I figured it out.

if t > 0
    alert(message='Buy TSE', freq=alert.freq_once_per_bar)
    
if t < 0
    alert(message='Sell TSE', freq=alert.freq_once_per_bar)