pub trait WidgetUnitData {
// Required method
fn id(&self) -> &WidgetId;
// Provided method
fn get_children(&self) -> Vec<&WidgetUnit> { ... }
}
pub trait WidgetUnitData {
// Required method
fn id(&self) -> &WidgetId;
// Provided method
fn get_children(&self) -> Vec<&WidgetUnit> { ... }
}