class VolatilitySurface implements VolatilityModel<DoublesPair> {

  @Override
  public Double getVolatility(final DoublesPair xy) {
    ArgumentChecker.notNull(xy, "xy pair");
    return _surface.getZValue(xy);
  }

  public  VolatilitySurface(Surface<Double, Double, Double> surface);
  public  VolatilitySurface(Surface<Double, Double, Double> surface, List<Tenor> expiryTenors);

}