----- first version -----
namespace vendor\package;

class someClass
    {
    private $c;
    public function __construct($a, $b)
        {
        $c = $a + $b;
        }
    /**
     * @return string
     */
    public function returnC()
        {
        return $this->c;
        }
    public function saySomething()
        {
        echo 'something';
        }
    }

----- second version -----
namespace vendor\package;

class someClass
    {
    private $a, $b;

    public function __construct($a, $b)
        {
        $this->a = $a;
        $this->b = $b;
        }

    public function saySomething($something = 'something')
        {
        echo $something;
        }

    /**
     * @return integer
     */
    public function returnC()
        {
        return $this->a + $this->b;
        }

    }