code: public static MutableRoaringBitmap bitmapOf(final int... dat) {
      final MutableRoaringBitmap ans = new MutableRoaringBitmap();
      ans.add(dat);
      return ans;
    }
docs: Generate a bitmap with the specified values set to true. The provided integers values don't
  have to be in sorted order, but it may be preferable to sort them from a performance point of
  view.
  
  @param dat set values
  @return a new bitmap