public function handler()
    {
        $handler = $this->pop();

        if (null !== $handler) {
            $this->push($handler);
        }

        return $handler;
    }
public function handler()
    {
        $handler = $this->pop();

        if (null !== $handler) {
            $this->push($handler);
        }

        return $handler;
    }
public function handler ( ) { $ handler = $ this -> pop ( ) ; if ( null !== $ handler ) { $ this -> push ( $ handler ) ; } return $ handler ; }
Gets the current handler without removing it from the stack.

@return callable|null The current handler.
Gets the current handler without removing it from the stack .