title: Override get value function from a custom FormControl
body: <p>I'm trying to create a custom form control on angular2 and I facing an issue when I try to get the value of all the form</p>
  
  <pre><code>this.form_c.value
  </code></pre>
  
  <p>I want to override the get value of my custom form control</p>
  
  <p>I try to find if I can do something like, but no success</p>
  
  <pre><code>private _val:any;
  @Input set value(x:any) {
  ...this._val = x;
  }
  
  get value {
  return this._val + "My mod";
  }
  </code></pre>