sclass VarMap extends AbstractMap<S> {
  TreeMap<A, B> base = ciMap();

  public B get(Object key) {
    B b = additions.get(key);
    if (b != null) return b;
    return base.get(key);
  }
  
  public B put(S key, S value) {
    
    ret base.put(key, value);
  }
  
  public Set<Map.Entry<S, S>> entrySet() {
    ret base.entrySet();
  }
}