public function filterByLastname($lastname = null, $comparison = null)
    {
        if (null === $comparison) {
            if (is_array($lastname)) {
                $comparison = Criteria::IN;
            } elseif (preg_match('/[\%\*]/', $lastname)) {
                $lastname = str_replace('*', '%', $lastname);
                $comparison = Criteria::LIKE;
            }
        }

        return $this->addUsingAlias(UserPeer::LASTNAME, $lastname, $comparison);
    }