private static function parseParamOperator(&$value)
    {
        foreach (static::$operators as $testOperator) {
            // Does the value start with this operator?
            $operatorLength = strlen($testOperator);

            if (strncmp(
                StringHelper::toLowerCase($value),
                $testOperator,
                $operatorLength
            ) == 0
            ) {
                $value = mb_substr($value, $operatorLength);

                if ($testOperator == 'not ') {
                    return 'not';
                } else {
                    return $testOperator;
                }
            }
        }

        return '';
    }