> a generator expression always evaluates to True

@dengemann I don't understand why, could you elaborate? For me it never evaluates to True, unless there is a win_length that's smaller than tstep. I tried to understand why it should always evaluate to True and looked e.g. [here](http://stackoverflow.com/questions/16505456/how-exactly-does-the-python-any-function-work) but from there I understand that it's ok to use a generator expression instead of a list with any.