public function findWord($word)
    {
        $key = $this->collator->getSortKey($word);

        /* In intl > 3.0.0a1, the key now ends with a trailing NUL byte.
         * We remove it for backward-compatibility with older releases. */
        if (substr($key, -1) === "\0") {
            $key = substr($key, 0, -1);
        }

        $this->existsQuery->execute(array(':key' => $key));
        $res = $this->existsQuery->fetchColumn();
        $this->existsQuery->closeCursor();
        if ($res === false || $res === null) {
            return null;
        }
        return $res;
    }