   <td>apply a css fade transition to the tooltip</td>
             </tr>
             <tr>
               <td>placement</td>
               <td>string|function</td>
               <td>'right'</td>
               <td>how to position the popover - top | bottom | left | right</td>
             </tr>
             <tr>
               <td>selector</td>
               <td>string</td>
               <td>false</td>
               <td>if a selector is provided, tooltip objects will be delegated to the specified targ