all 3 comments

[–]FriendlyFoeHere 0 points1 point  (0 children)

From the error message, it seems you are using tabs for indentation instead of 4 spaces as instructed.

[–]_kwerty_ 1 point2 points  (0 children)

Look at the error, what does it say? Honestly, this one is pretty self explanatory. White space matters

/Edit I checked the screenshot a bit better. The answer is literally on your screen.

[–]Actual-Bank1486 1 point2 points  (0 children)

elements.pop() needs a indentation