How is this code working?

Question

a = [0,1,2,3]
for a[-1] in a:
print (a[-1])
#output:[0,1,2,2]
#a becomes [0,1,2,2]
Why does a change.?

Answer 1

This is a bad practice only for brain teaser.

Consider it as for item in a
the value of item changes from 0, 1, 2 to 3 in each iteration.

Now the indicator becomes a[-1] (last element in the list a).
So in the first three iterations, a[-1] changes from 0, 1 to 2.
And in the fourth iteration, as its value is now 2, the last output is 2.

Answer 2

https://www.sololearn.com/Discuss/2130302/can-you-explain-the-output
https://www.sololearn.com/Discuss/1706938/JUMP_LINK__&&__python__&&__JUMP_LINK-quiz-how-does-this-work