src/Debug/Debug.php
private static function getMethodDefaultArgs($methodName)
    {
        $defaultArgs = array();
        if (isset(self::$methodDefaultArgs[$methodName])) {
            $defaultArgs = self::$methodDefaultArgs[$methodName];
        } elseif (\method_exists(self::$instance, $methodName)) {
            $reflectionMethod = new ReflectionMethod(self::$instance, $methodName);
            $params = $reflectionMethod->getParameters();
            foreach ($params as $reflectionParameter) {
                $defaultArgs[] = $reflectionParameter->isOptional()
                    ? $reflectionParameter->getDefaultValue()
                    : null;
            }
            self::$methodDefaultArgs[$methodName] = $defaultArgs;
        }
        return $defaultArgs;
    }
private static function getMethodDefaultArgs($methodName)
    {
        $defaultArgs = array();
        if (isset(self::$methodDefaultArgs[$methodName])) {
            $defaultArgs = self::$methodDefaultArgs[$methodName];
        } elseif (\method_exists(self::$instance, $methodName)) {
            $reflectionMethod = new ReflectionMethod(self::$instance, $methodName);
            $params = $reflectionMethod->getParameters();
            foreach ($params as $reflectionParameter) {
                $defaultArgs[] = $reflectionParameter->isOptional()
                    ? $reflectionParameter->getDefaultValue()
                    : null;
            }
            self::$methodDefaultArgs[$methodName] = $defaultArgs;
        }
        return $defaultArgs;
    }
Get Method's default argument list

@param string $methodName Name of the method

@return array