code: public static <O> RangeQuery<O> getRangeQuery(Relation<O> relation, DistanceFunction<? super O> distanceFunction, Object... hints) {
      final DistanceQuery<O> distanceQuery = relation.getDistanceQuery(distanceFunction, hints);
      return relation.getRangeQuery(distanceQuery, hints);
    }
docs: Get a range query object for the given distance function for radius-based
  neighbor search. (Range queries in ELKI refers to radius-based ranges, not
  rectangular query windows.)
  
  An index is used when possible, but it may fall back to a linear scan.
  
  Hints include:
  <ul>
  <li>Range: maximum range requested</li>
  <li>{@link de.lmu.ifi.dbs.elki.database.query.DatabaseQuery#HINT_BULK} bulk
  query needed</li>
  </ul>
  
  @param relation Relation used
  @param distanceFunction Distance function
  @param hints Optimizer hints
  
  @param <O> Object type
  @return KNN Query object