protected function decodeField($tsvField)
    {
        if (false === stripos($tsvField, static::DELIMITER)) {
            throw new \RuntimeException(sprintf('Could not unserialize LTSV field(%s).', $tsvField));
        }

        // "label:value"
        // "label:" (no value)
        return explode(static::DELIMITER, $tsvField, 2);
    }