Just a suggestion on terminology here: 'The depth() method should return the maximum number of nodes one would need to visit to get from the current node to an empty node'

The depth of a node in a tree is calculated from the root (depth 0) to where the node is. On the other hand, height is calculated from the furthest leaf node (height 0) to the level at which the node is. While it's not exactly what is described by the problem, I feel height is more resemblant of what is being asked.

I knew there must have been a better way than to copy and paste the code for each of the 9 digits... after looking at other people's solutions I see now this could have been executed much much much more elegantly, haha!

got it, thanks for the tips! still new at this, hah!

Same, I also did a chunky and ugly looking loop that checks against a list of month names haha... it looks like a disgrace next to this solution. But that's what's so cool about codewars! You're learning new practices all the time :)

Wow, thanks, that solved it for me -- I didn't even think about that :)