itertools 'previous' (opposite of next) python

Question

I'm currently using something like

>> import itertools
>> ABC = [a, b, c]
>> abc = itertools.cycle( ABC )
>> next( abc )
a
>> next( abc )
b    
>> next( abc )
c

I want my next call to be

>> previous( abc )
b

Is there a method in itertools that can accomplish this?

Answer 1

No, there isn't.

Because of the way Python's iteration protocol works, it would be impossible to implement previous without keeping the entire history of the generated values. Python doesn't do this, and given the memory requirements you probably wouldn't want it to.