Label a string tree with a level index. A level index is a string that looks like:
1.3.11.2. The last number is the index of the node in its parent, the number
before that is the index of the parent in its parent, and so on, so that they
form the unique path between the node and the tree root.
Label a string tree with a level index. A level index is a string that looks like:
1.3.11.2. The last number is the index of the node in its parent, the number before that is the index of the parent in its parent, and so on, so that they form the unique path between the node and the tree root.drill will get a child from a tree at a path.