code: public Container ior(Container x) {
      if (x instanceof ArrayContainer) {
        return ior((ArrayContainer) x);
      } else if (x instanceof BitmapContainer) {
        return ior((BitmapContainer) x);
      }
      return ior((RunContainer) x);
    }
docs: Computes the in-place bitwise OR of this container with another (union). The current container
  is generally modified, whereas the provided container (x) is unaffected. May generate a new
  container.
  
  @param x other container
  @return aggregated container