public void deleteExistingResults(){
  ArrayList<Key> keys=new ArrayList<Key>();
  List<Entity> results=getResults();
  for (  Entity entity : results) {
    keys.add(entity.getKey());
  }
  service.delete(keys);
}

public void deleteExistingResults ( ) { ArrayList < Key > keys = new ArrayList < Key > ( ) ; List < Entity > results = getResults ( ) ; for ( Entity entity : results ) { keys . add ( entity . getKey ( ) ) ; } service . delete ( keys ) ; }
removes any existing results for the user from the datastore .
