public Fluent returns(Function<String, Void> checker) throws ParseException {

    final Ast.Program program = parseProgram(pig);

    final PigRelBuilder builder =

        PigRelBuilder.create(PigRelBuilderTest.config().build());

    final StringWriter sw = new StringWriter();

    new CalciteHandler(builder, sw).handle(program);

    checker.apply(Util.toLinux(sw.toString()));

    return this;

  }