So in the unpacked tuple, when you modify "last", it's like you're ... appending information onto just that piece. I'm a very visual person, so this might make no sense, but this is the image I have: the tuple as a shark and the change to the unpacked tuple as a remora. The remora comes up and attaches to, let's say the shark's fin, and therefore becomes something that has to be considered with regards to drag and velocity, but it doesn't intrinsically change the fin of the shark and if you tore the remora off, the shark fin would still be the same.

Stacks as books and queues as a line of customers... got it!