    @Test
    public void testVariable(){

        // using strings
        Transformation t = new Transformation();
        t.variable("$foo", 10)
                .chain()
                .ifCondition(faceCount().gt(2))
                .crop("scale")
                .width(new Condition("$foo * 200 / faceCount"))
                .endIf();
        assertEquals("$foo_10/if_fc_gt_2/c_scale,w_$foo_mul_200_div_fc/if_end", t.generate());
    }