case REMOVE_INDEX:
RemoveIndex removeIndex = (RemoveIndex) u;
System.out.println("\t# {parentId: " + removeIndex.getParentId()+ ", id: " + removeIndex.getId() + "}");
break;
case REMOVE_CHILDREN:
RemoveChildren removeChildren = (RemoveChildren) u;
System.out.println("\t! {id: " + removeChildren.getId() + "}");
break;
case TERMINATE_HEAP:
System.out.println("\t! TERMINATE HEAP");
break;
default: