/**
* Check if an action already exists
*
* @param array $args e.g. array('userid'=>4, 'key'=>'post', 'value'=>'6408')
* @return bool
*/
public function activityExists($args = array())
{
require_once LIBS . 'UserActivity.php';
$activity = new UserActivity();
return $activity->activityExists($this, $args);
}