code: private static Map<Direction, Map<Parity, String>> createDirectionParityMap() {
          Map<Direction, Map<Parity, String>> m = newHashMap();
          m.put(Direction.BOTTOM, GeoHash.<Parity, String> newHashMap());
          m.put(Direction.TOP, GeoHash.<Parity, String> newHashMap());
          m.put(Direction.LEFT, GeoHash.<Parity, String> newHashMap());
          m.put(Direction.RIGHT, GeoHash.<Parity, String> newHashMap());
          return m;
      }
docs: Create a direction and parity map for use in adjacent hash calculations.
  
  @return map