Repository: yt-dlp/yt-dlp
File: yt_dlp/extractor/facebook.py (Python)

Code before:
                        info['title'] = description or 'Facebook video #%s' % v_id
                    entries.append(info)

                def parse_attachment(attachment, key='media'):
                    media = attachment.get(key) or {}
                    if media.get('__typename') == 'Video':
                        return parse_graphql_video(media)

                nodes = variadic(traverse_obj(data, 'nodes', 'node') or [])
                attachments = traverse_obj(nodes, (
                    ..., 'comet_sections', 'content', 'story', (None, 'attached_story'), 'attachments',
                    ..., ('styles', 'style_type_renderer', ('throwbackStyles', 'attachment_target_renderer')),
                    'attachment', {dict}))
                for attachment in attachments:
                    ns = traverse_obj(attachment, ('all_subattachments', 'nodes', ..., {dict}),
                                      ('target', 'attachments', ..., 'styles', 'attachment', {dict}))
                    for n in ns:
                        parse_attachment(n)
                    parse_attachment(attachment)

                edges = try_get(data, lambda x: x['mediaset']['currMedia']['edges'], list) or []
                for edge in edges:
                    parse_attachment(edge, key='node')

                video = (traverse_obj(data, ('event', 'cover_media_renderer', 'cover_video', {dict}))  # event cover video
                         or data.get('video') or {})
                if video:
                    attachments = try_get(video, [
                        lambda x: x['story']['attachments'],
                        lambda x: x['creation_story']['attachments']
                    ], list) or []
                    for attachment in attachments:
                        parse_attachment(attachment)
                    if not entries:
                        parse_graphql_video(video)

                if len(entries) > 1:
                    return self.playlist_result(entries, video_id)

                video_info = entries[0] if entries else {'id': video_id}
                webpage_info = extract_metadata(webpage)
                # honor precise duration in video info
                if video_info.get('duration'):
                    webpage_info['duration'] = video_info['duration']
                return merge_dicts(webpage_info, video_info)

        if not video_data:
            m_msg = re.search(r'class="[^"]*uiInterstitialContent[^"]*"><div>(.*?)</div>', webpage)
            if m_msg is not None:
                raise ExtractorError(
                    'The video is not available, Facebook said: "%s"' % m_msg.group(1),

Review comment (suggestion):
it's not good to do `traverse_obj(data, ...) or data.get(...)` when we can pass multiple paths to `traverse_obj` instead
```suggestion
                video = traverse_obj(data, (
                    'event', 'cover_media_renderer', 'cover_video'), 'video', expected_type=dict) or {}
```

Code after:
                def parse_attachment(attachment, key='media'):
                    media = attachment.get(key) or {}
                    if media.get('__typename') == 'Video':
                        return parse_graphql_video(media)

                nodes = variadic(traverse_obj(data, 'nodes', 'node') or [])
                attachments = traverse_obj(nodes, (
                    ..., 'comet_sections', 'content', 'story', (None, 'attached_story'), 'attachments',
                    ..., ('styles', 'style_type_renderer', ('throwbackStyles', 'attachment_target_renderer')),
                    'attachment', {dict}))
                for attachment in attachments:
                    ns = traverse_obj(attachment, ('all_subattachments', 'nodes', ..., {dict}),
                                      ('target', 'attachments', ..., 'styles', 'attachment', {dict}))
                    for n in ns:
                        parse_attachment(n)
                    parse_attachment(attachment)

                edges = try_get(data, lambda x: x['mediaset']['currMedia']['edges'], list) or []
                for edge in edges:
                    parse_attachment(edge, key='node')

                video = traverse_obj(data, (
                    'event', 'cover_media_renderer', 'cover_video'), 'video', expected_type=dict) or {}
                if video:
                    attachments = try_get(video, [
                        lambda x: x['story']['attachments'],
                        lambda x: x['creation_story']['attachments']
                    ], list) or []
                    for attachment in attachments:
                        parse_attachment(attachment)
                    if not entries:
                        parse_graphql_video(video)

                if len(entries) > 1:
                    return self.playlist_result(entries, video_id)

                video_info = entries[0] if entries else {'id': video_id}
                webpage_info = extract_metadata(webpage)
                # honor precise duration in video info
                if video_info.get('duration'):
                    webpage_info['duration'] = video_info['duration']
                return merge_dicts(webpage_info, video_info)

        if not video_data:
            m_msg = re.search(r'class="[^"]*uiInterstitialContent[^"]*"><div>(.*?)</div>', webpage)
            if m_msg is not None:
                raise ExtractorError(
                    'The video is not available, Facebook said: "%s"' % m_msg.group(1),
                    expected=True)
            elif any(p in webpage for p in (
                    '>You must log in to continue',