I'm new to object oriented programming and i am using python but i could not plot a Bollinger Band on output chart. I found the code lines:

var bb = BB(Symbol symbol, int period, decimal k, MovingAverageType movingAverageType = null, Resolution resolution = null, Func`2[Data.IBaseData,Decimal] selector = null)

Plot<T>(string chart, params IndicatorBase<T>[] indicators) where T : BaseData

I could not even apply Bollinger Band with periods=20 and k=2, so i did not try to plot it. May you write a basic sample python code or just tell where to write them ?