public function map($callable)
    {
        // Contain the map within a higher-order callable
        // that enforces type-correctness for the $callable
        $this->frames = array_map(function ($frame) use ($callable) {
            $frame = call_user_func($callable, $frame);

            if (!$frame instanceof Frame) {
                throw new UnexpectedValueException(
                    "Callable to " . __METHOD__ . " must return a Frame object"
                );
            }

            return $frame;
        }, $this->frames);

        return $this;
    }