code: public static <K, V> RubyHash<K, V> rh(K key, V value) {
      RubyHash<K, V> rh = newRubyHash();
      rh.put(key, value);
      return rh;
    }
docs: Creates a {@link RubyHash} by given key-value pair.
  
  @param <K>
  the type of the key elements
  @param <V>
  the type of the value elements
  @param key
  of entry
  @param value
  of entry
  @return {@link RubyHash}