public function expectedIs($type)
    {
        // If people set type = message type, return true
        if (is_array($this->body) && isset($this->body['attachment']) && isset($this->body['attachment']['type'])) {
            return true;
        }

        if (is_string($this->body)) {
            $fileExtension = $this->detectMediaType($this->body);
            return $fileExtension === $type;
        }

        // If it's string, maybe it's URL. Check the extension
        if (isset($this->body['attachment']) && is_string($this->body['attachment']['payload']['url'])) {
            $fileExtension = $this->detectMediaType($this->body['attachment']['payload']['url']);
            return $fileExtension === $type;
        }

        return false;
    }