python list concatenation

I think I can't use append bc extends appends
I need extend because it creates a copy of sub
if I have sublists = ], [1 and im going to add 2
appending 2 to [] will leave me with sublists = 2], [1,2.
So I need to create copies

myList.extend([1,2]) is the same as myList += [1,2]. except that += doesn't work for non local variables and cant be used as chained funciton call