Python has had proper closures since version 2.2, which is quite old at this point. You can verify this using the following code: def func(): x = [

Python has had proper closures since version 2.2, which is quite old at this point. You can verify this using the following code: def func(): x = [] def func2(): x.append(1) return x return func2 closed = func(); closed(); assert closed() == [1,1] closed = func(); closed(); assert closed() == [1,1]