public void add(Gondola gondola){
  extras.add(gondola);
}

public void add ( Gondola gondola ) { extras . add ( gondola ) ; }
add other gondola instances to this rc . currently only used to help advance the clock of these extra instances . the gondola instance will be forgotten when stop ( ) is called . neither start ( ) nor stop ( ) will not be called on the supplied gondola instance .
