Example in README is confusing

I don't follow the [example](https://github.com/duojs/gulp#example) in the README.

``` js
var gulp = require('duo-gulp');
```

Is there any other way to use this plugin without wrapping `gulp`?

``` js
var duo = Duo(root).entry(entry);
```

What is `root` and `entry`?

``` js
duo.run(fn);
```

What is `fn`?
