Python list comprehension - access last created element?

Question

Is it possible to access the previous element generated in a list comprehension.

I am working on some toy encryption stuff. Given the key as an arbitrarily large in

Answer 1

I would prefer to use something more like enumerate generator

def emit_previous(iterable, initial=None):
    previous = initial
    for item in iterable:
        yield previous, item
        previous = item

cipher = []
for previous, element in emit_previous(message, initial=initialization_value):
    seed = element ^ previous ^ key
    cipher.append(seed)