sclass Schedule<A> {
  TreeMultiMap<Seconds, A> entries;
  new TreeMap<Seconds> jumps;
  
  void add(double seconds, A a) {
    entries.put(Seconds(seconds), a);
  }
  
  void jumpFromTo(double from, double to) {
    jumps.put(from, to);
  }
  
  void speedUp(double factor) {
    entries = (TreeMultiMap) mapMultiMapKeys(entries,
      seconds -> seconds/factor);
  }
}