rather than `for .. in` loops, prefer `Object.keys()` instead - it's much faster on v8, also it's better to put the conditional outside the loop - if ridFormat is not string we can avoid it entirely.

```js
if (this.server.ridFormat === 's') {
  var keys = Object.keys(value),
      total = keys.length;
      key, i;
  for (i = 0; i < total; i++) {
    if (value[i] instanceof RID) {
      value[i] = ''+value[i];
    }
  }
}
```