Nix: List contents of directories in a tree-like format

Why don’t I use this command more?

$ tree
.
├── CONTRIBUTING.md
├── Gemfile
├── Gemfile.lock
├── LICENSE
├── README.md
├── aws
│   ├── cli-assuming-a-role.md
│   ├── cli-list-account-aliases.md
│   └── cli-modify-volume-size.md
...