问将该段 Pine-Script V2转为V4版？

//@version=2
Factor=input(1, minval=1,maxval = 000, title="Trend Transition Signal")
Pd=input(1, minval=1,maxval = 100)
Up=hl2-(Factor*atr(Pd))
Dn=hl2+(Factor*atr(Pd))
TrendUp=close[1]>TrendUp[1]? max(Up,TrendUp[1]) : Up
TrendDown=close[1]<TrendDown[1]? min(Dn,TrendDown[1]) : Dn
Trend = close > TrendDown[1] ? 1: close< TrendUp[1]? -1: nz(Trend[1],0)
plotarrow(Trend == 1 and Trend[1] == -1 ? Trend : na, title="Up Entry Arrow", colorup=lime, maxheight=1000, minheight=50, transp=85)
plotarrow(Trend == -1 and Trend[1] == 1 ? Trend : na, title="Down Entry Arrow", colordown=red, maxheight=1000, minheight=50, transp=85)