是否可以在 Tradingview 的布林线策略中添加止损和止盈值？

Question

strategy("Bollinger Bands Strategy", overlay=true)
source = close
length = input(20, minval=1)
mult = input(2.0, minval=0.001, maxval=50)
basis = sma(source, length)
dev = mult * stdev(source, length)
upper = basis + dev
lower = basis - dev
buyEntry = crossover(source, lower)
sellEntry = crossunder(source, upper)
if (crossover(source, lower))
    strategy.entry("BBandLE", strategy.long, stop=lower, oca_name="BollingerBands", oca_type=strategy.oca.cancel, comment="BBandLE")
    
else
    strategy.cancel(id="BBandLE")

if (crossunder(source, upper))
        strategy.entry("BBandSE", strategy.short, stop=loss=8, oca_name="BollingerBands", oca_type=strategy.oca.cancel, comment="BBandSE")
else
    strategy.cancel(id="BBandSE")

我想在这里添加止损。因为我是新手，所以我遇到了很多错误。我收到变量错误，并且 if 语句的返回与其他语句不匹配。