anchor.diff:    }
   }
   
  +List _removeTrailingNulls(List args) {
  +  while (args.isNotEmpty && args.last == null) {
  +    args.removeLast();
  +  }
  +  return args;
  +}
  +
   List _removeNulls(List args) {
     args.removeWhere((args) => args == null);
     return args;
  
positive.code:    * The unique name generated by push() is prefixed with a client-generated
     * timestamp so that the resulting list will be chronologically sorted.
     */
     Firebase push({value}) => new Firebase.fromJsObject(_fb.callMethod('push', _removeNulls([value])));
  
     /**
      * Write data to a Firebase location, like set(), but also specify the
  
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
  