Hi, I'm new to QuantConnect and I'm having some trouble with Rolling Windows. 

In my code I initialize a rolling window like this 

After filling the window I wanted to find the max high price of the bars in the window but skipping the most recent element like this:  

self.maxHigh = max(self.TradeBarWindow[1:], key = lambda y: y.High).High

but it gives me an error of method. However If I erase the brackets, it works fine, but it considers the high value of the most recent element also.

Another thing that is bugging me is the fact that I created a list and then appended the rolling window to it, but then if I try to access its elements like "High" or "Close", it throws me an error also.

newArrayTradeBar = [ ]
#Can't access the element newArrayTradeBar[0].Close for example, despite the fact that newArrayTradeBar[0] returns me a TradeBar class element

What am I missing?