WKT Example

Hi, can jou provide a WKT example. What I tried:
```javascript
var vector = new ol.layer.Vector({
     source: new ol.source.Vector({
           parser: new ol.parser.WKT(),
           data: 'POLYGON((10.689697265625 -25.0927734375, 34.595947265625 -20.1708984375, 38.814697265625 -35.6396484375, 13.502197265625 -39.1552734375, 10.689697265625 -25.0927734375))' 
     })
});
```