interface IDoubleBuffer extends IntSize, Iterable<Double>, IntegrityCheckable {
  void add(double d);
  void addAll(Iterable<Double> l);
  double[] toArray();
  double get(int idx);
  void trimToSize();
  double popLast();
  double first();
  double last();
  bool isEmpty();
  void insertAt(int idx, double[] l);
  int indexOf(double d);
  default bool contains(double d) { ret indexOf(d) >= 0; }
}