/**
  * Given a list of token names, suppress all tokens that have not been validated, and
  * return the non-validated token with the highest priority
  *
  * @param array $keys List of token keys in ascending priority (low to high)
  * @return ParameterConfirmationToken The token container for the unvalidated $key given with the highest priority
  */
 public static function prepare_tokens($keys)
 {
     $target = null;
     foreach ($keys as $key) {
         $token = new ParameterConfirmationToken($key);
         // Validate this token
         if ($token->reloadRequired()) {
             $token->suppress();
             $target = $token;
         }
     }
     return $target;
 }