Help creating an new indicator that will calculate and return a single result as output

Hi guys, I found a problem while creating multiple SMAs and trying to use it as source in standard deviation it’s not possible to add up these SMAs, it says operator ‘+’ cannot be applied to operands of type ’SimpleMoving Average’ and ’SimpleMoving Average’, can you help me with the problem?

eg:

var sma1 = Indicators.SimpleMovingAverage(Bars.ClosePrices, 50);

var sma2 = Indicators.SimpleMovingAverage(Bars.ClosePrices, 100);

var sma3 = Indicators.SimpleMovingAverage(Bars.ClosePrices, 150);

var sma4 = Indicators.SimpleMovingAverage(Bars.ClosePrices, 200);

var sma_1234 = (((sma1+sma2)/2) + ((sma3+sma4)/2))/2

var sd = Indicators.StandardDeviation(sma_1234.Result,50, MovingAverageType.Simple);

var sma_1234 = (((sma1+sma2)/2) + ((sma3+sma4)/2))/2 this is the part where it cannot do it in robot it has to be done it alone in an new indicator calculate and return a single result as output, but I am too new to code, could anyone please help with the indicator code? Much appreciated !