What does locals()['_[1]'] mean in Python?

Question

I saw a one liner code that is claimed to remove duplicates from a sequence:

u = [x for x in seq if x not in locals()[\'_[1]\']]

I tried th

Answer 1

Wow! That's nastily cryptic code. Took a bit of research to find the answer.

Basically the list comprehension is building a new list. It names this temporary list _[1]. The locals() part is just using the locals() dictionary to look up that name, as it's not accessible otherwise. So that line is saying...

[x for x in seq if x not in this_list]

Cryptic.

The found information on this here