Is there a way to catch this unexpected value

[(9, '['), (25, ']'), (442, '['), (460, ']'), (558, '['), (576, ']'), (608, ']')]

In this list of tuples I am trying to find key of "]" in the end.
If you take a closer look values goes like this;

[ => ] => [ => ] => [ => ] => [ => ]

But at last step it goes;

] => ]

I want to find key when this unexpected value appear.
How can I do that?

>Solution :

I think you’re looking for something like this:

from itertools import cycle

L = [(9, '['), (25, ']'), (442, '['), (460, ']'), (558, '['), (576, ']'), (608, ']')]
c = cycle(['[', ']'])

for t in L:
    if t[1] != next(c):
        print(t[0])
        break