private void checkStatementThatIgnoresInput(Expression exp) {
        assertOptimized(new StatementExpression(new InputExpression("xyzzy"), exp), exp);
        assertOptimized(new StatementExpression(new InputExpression("xyzzy"), exp, new LowerCaseExpression()),
                        new StatementExpression(exp, new LowerCaseExpression()));
    }
@author <a href="mailto:magnarn@yahoo-inc.com">Magnar Nedland</a>
indexinglanguage/src/test/java/com/yahoo/vespa/indexinglanguage/ExpressionOptimizerTestCase.java