Recusive

A tree that nests into itself. Add a root node, open it, add a child under it, open that child, add one of its own — every node can hold more nodes, exactly as deep as you take it. No fixed limit on the structure; it grows only as far as the tree you actually build.

15 nodes

5 levels deep

Add a root node

hi depth 0
- gf depth 1
  
  gdf
  - sd depth 2
    - dfg depth 3
      - hgdf depth 4
        
        gnvb depth 5
        
        wq depth 5
      - qw depth 4
      - wq depth 4
    - wq depth 3
  - qw depth 2
  - qw depth 2
- sdf depth 1
  - qw depth 2
- qw depth 1