Take the first `n` values that are emitted through the stream.
<aside>
```js
// take(n): Stream
var stream = Rafa.stream();
var values= [];
stream.take(2).each(v => values.push(v));
stream.enumerate(Rafa.Enumerator.array([1,2,3,4]));
//values: [1,2]
```
</aside>