The tree from the videos:
stateDiagram-v2 Fruits --> Apple Fruits --> Mango Apple --> Green_Apple Apple --> Yellow_Apple Apple --> Red_Apple 
- Starting video
- 🐾 Adjacency List Model in SQL 🐾 Playlist
- 🐉 Nested sets trees 🐉 Playlist
- 🔱 Graphs & trees 🔱 Playlist
- code
- https://github.com/Rowadz/nested-sets-trees-model-yt