yes, on my previous projects I always used [mout/string/interpolate](http://moutjs.com/docs/latest/string.html#interpolate) instead of concatenation.. we could do a simple `String#replace` in this case, but I don't think it improves that much:

```js
var block = ('.%id%selector, .%id %selector { %body }')
  .replace(/%id/g, calendarId)
  .replace(/%selector/g, selector)
  .replace(/%body/g, body);
```