Awesome Cumulative Volume Oscillator

//@version=5
indicator("Awesome Cumulative Volume Oscillator", "ACVO", overlay=false)
series          =   input(50, "length")
bs_isfirst      =   ta.barssince(barstate.isfirst)+1
weight_volume   =   (ta.change(close)/close[1]) * volume
cum_volume      =   ta.cum(weight_volume) / bs_isfirst
[middle, upper, lower]  =   ta.bb(cum_volume, series, 1)
sma_isfirst     =   ta.cum(cum_volume)/(bs_isfirst)
isfirst_ma      =   series>bs_isfirst? sma_isfirst :middle
cum_m_ma        =   cum_volume-isfirst_ma
plot(cum_m_ma, title="Cumulative Volume Deviation")
plot(0, color=color.red, title="Zero-Line", display=display.pane)
plot(upper-isfirst_ma, "Upp-Deviation", color=color.black, display=display.pane)
plot(lower-isfirst_ma, "Down-Deviation", color=color.black, display=display.pane)