title: Angular 2 Mutually exclusive checkboxs
body: <p>I have 2 checkboxes, when one is checked the other have to be unchecked, is there any way, using ngModel to block the selection of the other when one of them is already selected ?</p>
  
  <pre><code>                    &lt;input type="checkbox" class="filled-in" id="checkIn" [(ngModel)]="checkboxFlag" checked /&gt;
                      &lt;label id="labelIn" for="checkIn"&gt; Inbound&lt;/label&gt;
                      &lt;input type="checkbox" class="filled-in" id="checkOut"  /&gt;
                      &lt;label id="labelOut" for="checkOut"&gt; Outbound&lt;/label&gt;
  </code></pre>