Alright, another Data Structure lesson. Tree Structures are sorted using nodes (the slots), which are Parents and Children. Parents are the starting point, so the violin is the parent since it was stored first. When Rose took the knitting bag, that because the violin’s ‘child’ hence the connection. When it says LEFT LEAF, it just states what spot the card is at in relation to the parent. If it was RIGHT LEAF, it would be in the third slot

And that is a lot more information you would need in order to understand the comic