nicegui/website/more_documentation/tree_documentation.py

from nicegui import ui


def main_demo() -> None:
    ui.tree([
        {'id': 'numbers', 'children': [{'id': '1'}, {'id': '2'}]},
        {'id': 'letters', 'children': [{'id': 'A'}, {'id': 'B'}]},
    ], label_key='id', on_select=lambda e: ui.notify(e.value))