private void assertOptimized(Expression input, Expression expected) {
        assertEquals(expected.toString(), new ExpressionOptimizer().convert(input).toString());
    }
@author <a href="mailto:magnarn@yahoo-inc.com">Magnar Nedland</a>
indexinglanguage/src/test/java/com/yahoo/vespa/indexinglanguage/ExpressionOptimizerTestCase.java