anchor.diff:     * restrictive queries.
      */
     Query startAt({int priority, String name}) =>
  -      new Query.fromJsObject(_fb.callMethod('startAt', _removeNulls([priority, name])));
  +      new Query.fromJsObject(_fb.callMethod('startAt', _removeTrailingNulls([priority, name])));
   
     /**
      * Create a Query with the specified ending point. The ending point is
  
positive.code:   }
  }
  
  List _removeNulls(List args) {
    args.removeWhere((args) => args == null);
    return args;
  
negative.code:    * restrictive queries.
     */
    Query endAt({int priority, String name}) =>
        new Query.fromJsObject(_fb.callMethod('endAt', _removeTrailingNulls([priority, name])));
  
    /**
     * Queries are attached to a location in your Firebase. This method will
  