var stylus = require('./'); const value = ` $IMG = { temp: { selectors: ("test" "test1") props: { pop: "dies" } } } add-property(name, expr) {name} expr generateImgClasses() for $img, $obj in $IMG {join(",", $obj.selectors)} for $prop in $IMG add-property($prop, "url(%s)" % $img) html generateImgClasses()`; stylus(value).render((err, css) => { if (err) { throw err; } console.log(css); });