removed property
      
      Future<void> 
      get
      removed
      
    
    
A future that completes when this component is removed from its parent.
If the component is already removed (see isRemoved), this returns an already completed future.
Implementation
Future<void> get removed {
  return isRemoved
      ? Future.value()
      : (_removeCompleter ??= Completer<void>()).future;
}