class Elt {

  @Udf
  public String elt(
      @UdfParameter(description = "the nth element to extract") final int n,
      @UdfParameter(description = "the strings of which to extract the nth") final String... args
  ) {
    if (n < 1 || n > args.length) {
      return null;
    }

    return args[n - 1];
  }

}