expandKeys method
Implementation
void expandKeys(Iterable<K> keys) {
if (keys.isEmpty) return;
final newExpandedKeys = copyKeySet(expandedKeys)..addAll(keys);
updateExpansionState(newExpandedKeys);
}
void expandKeys(Iterable<K> keys) {
if (keys.isEmpty) return;
final newExpandedKeys = copyKeySet(expandedKeys)..addAll(keys);
updateExpansionState(newExpandedKeys);
}