src/Valkyrja/Http/NativeResponse.php
public function getAge(): int
    {
        if (null !== $age = $this->headers->get('Age')) {
            return $age;
        }

        return max(
            time() - date('U', strtotime($this->getDateHeader())),
            0
        );
    }
public function getAge(): int
    {
        if (null !== $age = $this->headers->get('Age')) {
            return $age;
        }

        return max(
            time() - date('U', strtotime($this->getDateHeader())),
            0
        );
    }
Returns the age of the response.

@throws \RuntimeException

@return int The age of the response in seconds