What is the difference between Slice class and Tradebar class.
I got an Slice  error in an example I ran in lean, but when I put TradeBar in place,  the program ran.
Did I miss something in the meantime or are Slice  and Tradebar one thing?
Do I need to import something like
from QuantConnect.Data.Market import TradeBar
There is no problem with line of my code in quantconnect/terminal

def Initialize(self): self.window = RollingWindow[Slice](500)

but there was a problem in lean, and I replaced that with

from QuantConnect.Data.Market import TradeBar def Initialize(self): self.window = RollingWindow[Tradebar](500)