code: public static <E> RubyHash<E, E> Hash(
        Collection<? extends Collection<? extends E>> cols) {
      RubyHash<E, E> rubyHash = newRubyHash();
      for (Collection<? extends E> col : cols) {
        if (col.size() < 1 || col.size() > 2) throw new IllegalArgumentException(
            "ArgumentError: invalid number of elements (" + col.size()
                + " for 1..2)");
        Iterator<? extends E> iter = col.iterator();
        rubyHash.put(iter.next(), iter.hasNext() ? iter.next() : null);
      }
      return rubyHash;
    }
docs: Turns a {@link Collection} of Lists into a {@link RubyHash}.
  
  @param <E>
  the type of the elements
  @param cols
  a {@link Collection} of Collections
  @return {@link RubyHash}