public static function getExistingMethodSlot(ClassMethod $method)
    {
        $className = $method->getClassDefinition()->getCompleteName();
        $methodName = $method->getName();

        if (isset(self::$cacheMethodSlots[$className][$methodName])) {
            return self::$cacheMethodSlots[$className][$methodName];
        }

        return 0;
    }