code: public static Hash getInstance(int type) {
      switch(type) {
      case JENKINS_HASH:
        return JenkinsHash.getInstance();
      case MURMUR_HASH:
        return MurmurHash.getInstance();
      default:
        return null;
      }
    }
docs: Get a singleton instance of hash function of a given type.
  @param type predefined hash type
  @return hash function instance, or null if type is invalid