Flutter Fancy Tree View Example geographicalLocationsTree data structure type?

[DktPhl2019]

Hello

I am looking at the Flutter Fancy Tree View Example tree_data.dart file variable: geographicalLocationsTree

I don't understand the data structure for this variable.

I would like to dynamically add items to a list and show the list in the tree view.

Could you please specify the data structure for this variable: geographicalLocationsTree

Thank You