We see that the tree is huge. The depth of leaf nodes might be variable, but we need to consider all possible root-to-leaf paths.
Given the structure, the longest path from root to a leaf would go through the longest chain in this nested tree. Let's analyze:
The outermost `Tree` has two children: a leaf `leaf0`, and a `Tree leaf1`. So at least one child is a leaf. The other child is a subtree with just leaf1.
Then that subtree is a Tree with a single node leaf2, and the rest of the tree continues as a chain.
Actually the pattern is:
Root: Tree (leaf0 : subtree) where subtree = Tree (leaf1 : rest) where rest = Tree (leaf2 : Tree (leaf3 : ...)). So it's basically a single path of length 4? Wait no, each step adds a new leaf at the front. Actually let's illustrate:
