При компиляции кода на Pine v5 выдает ошибку - no viable alternative at input 'length', как это можно решить?

//@version=2
//==@version=5
  strategy("EMA-BB", overlay=true)
  length = input(title="Length of EMA", type=integer, defval=20)
  ema = ema(close, length)
  upper = bollinger(close, length, 2)
  lower = bollinger(close, length, -2)

  // enter long trade when the price cross above EMA
  // and is within the upper Bollinger Band
  enterLong = crossover(close, ema) and close < upper

  // enter short trade when the price cross below EMA
  // and is within the lower Bollinger Band
  enterShort = crossunder(close, ema) and close > lower

  // exit long trades when price cross below EMA
  exitLong = crossunder(close, ema)
  // exit short trades when price cross above EMA
  exitShort = crossover(close, ema)

  // plot EMA and Bands
  plot(ema, title="EMA", color=blue)
  plot(upper, title="Upper Band", color=red)
  plot(lower, title="Lower Band", color=green)

  // enter and exit trades
  if (enterLong)
    strategy.entry("long", strategy.long)
  if (enterShort)
    strategy.entry("short", strategy.short)
  if (exitLong)
    strategy.close("long")
  if (exitShort)
    strategy.close("short")