/**
  * Create a new user mapping between a Wikia user account and a FB account
  *
  * @param int $wikiaUserId
  * @param int $fbUserId
  * @param string $bizToken
  *
  * @return FacebookMapModel|null Returns the mapping on success, null otherwise
  */
 public static function createUserMapping($wikiaUserId, $fbUserId, $bizToken = '')
 {
     $map = new self();
     $map->setBizToken($bizToken);
     $map->relate($wikiaUserId, $fbUserId);
     try {
         $map->save();
     } catch (\FacebookMapModelException $e) {
         return null;
     }
     return $map;
 }