code: public static <E> RubyArray<RubyArray<E>> ra(RubyArray<E> rubyArray) {
      RubyArray<RubyArray<E>> ra = newRubyArray();
      return ra.push(rubyArray);
    }
docs: Creates a {@link RubyArray} which contains the given {@link RubyArray}.
  
  @param <E>
  the type of the elements
  @param rubyArray
  a {@link RubyArray}
  @return {@link RubyArray} of {@link RubyArray}