How to use the mediacloud.tags.TAG_ACTION_REMOVE function in mediacloud

def remove_sources_from_collection(collection_id):
    source_ids_to_remove = request.form['sources[]'].split(',')
    source_ids_to_remove = [int(s) for s in source_ids_to_remove]
    user_mc = user_admin_mediacloud_client()
    # get the sources in the collection first, then remove and add as needed
    existing_source_ids = [int(m['media_id']) for m in media_with_tag(user_mediacloud_key(), collection_id)]
    source_ids_to_remain = list(set(existing_source_ids) - set(source_ids_to_remove))

    media_to_remove = [MediaTag(sid, tags_id=collection_id, action=TAG_ACTION_REMOVE) for sid in source_ids_to_remove]
    media_to_remain = [MediaTag(sid, tags_id=collection_id, action=TAG_ACTION_ADD) for sid in
                       source_ids_to_remain]  # do I need to run similar or TAG_ACTION_REMOVE?
    current_media = media_to_remove + media_to_remain

    if len(current_media) > 0:
        results = user_mc.tagMedia(current_media)

    apicache.invalidate_collection_source_representation_cache(user_mediacloud_key(), collection_id)
    return jsonify(results)

source_ids = [int(sid) for sid in request.form['sources[]'].split(',')]
    # first update the collection
    updated_collection = user_mc.updateTag(collection_id, formatted_name, label, description,
                                           is_static=(static == 'true'),
                                           show_on_stories=(show_on_stories == 'true'),
                                           show_on_media=(show_on_media == 'true'))
    # get the sources in the collection first, then remove and add as needed
    existing_source_ids = [int(m['media_id']) for m in media_with_tag(user_mediacloud_key(), collection_id)]
    source_ids_to_remove = list(set(existing_source_ids) - set(source_ids))
    source_ids_to_add = [sid for sid in source_ids if sid not in existing_source_ids]
    # logger.debug(existing_source_ids)
    # logger.debug(source_ids_to_add)
    # logger.debug(source_ids_to_remove)
    # then go through and tag all the sources specified with the new collection id
    tags_to_add = [MediaTag(sid, tags_id=collection_id, action=TAG_ACTION_ADD) for sid in source_ids_to_add]
    tags_to_remove = [MediaTag(sid, tags_id=collection_id, action=TAG_ACTION_REMOVE) for sid in source_ids_to_remove]
    tags = tags_to_add + tags_to_remove
    if len(tags) > 0:
        user_mc.tagMedia(tags)
        apicache.invalidate_collection_source_representation_cache(user_mediacloud_key(), collection_id)
    return jsonify(updated_collection['tag'])

{'form_key': 'publicationCountry', 'tag_sets_id': TAG_SETS_ID_PUBLICATION_COUNTRY},
        {'form_key': 'publicationState', 'tag_sets_id': TAG_SETS_ID_PUBLICATION_STATE},
        {'form_key': 'primaryLanguage', 'tag_sets_id': TAG_SETS_ID_PRIMARY_LANGUAGE},
        {'form_key': 'countryOfFocus', 'tag_sets_id': TAG_SETS_ID_COUNTRY_OF_FOCUS},
        {'form_key': 'mediaType', 'tag_sets_id': TAG_SETS_ID_MEDIA_TYPE}
    ]
    for metadata_item in valid_metadata:
        metadata_tag_id = request.form[metadata_item['form_key']] if metadata_item['form_key'] in request.form else None # this is optional
        existing_tag_ids = [t for t in source['media_source_tags'] if is_metadata_tag_set(t['tag_sets_id'])]
        # form field check
        if metadata_tag_id in [None, '', 'null', 'undefined']:
            # we want to remove it if there was one there
            if len(existing_tag_ids) > 0:
                for remove_if_empty in existing_tag_ids:
                    if metadata_item['tag_sets_id'] == remove_if_empty['tag_sets_id']:
                        tag = MediaTag(media_id, tags_id=remove_if_empty['tags_id'], action=TAG_ACTION_REMOVE)
                        user_mc.tagMedia([tag])

        elif metadata_tag_id not in existing_tag_ids:
            # need to add it and clear out the other
            tag = MediaTag(media_id, tags_id=metadata_tag_id, action=TAG_ACTION_ADD)
            user_mc.tagMedia([tag], clear_others=True)
    # result the success of the media update call - would be better to catch errors in any of these calls...
    return jsonify(result)

name = request.form['name']
    url = request.form['url']
    editor_notes = request.form['editor_notes'] if 'editor_notes' in request.form else None  # this is optional
    public_notes = request.form['public_notes'] if 'public_notes' in request.form else None  # this is optional
    monitored = request.form['monitored'] if 'monitored' in request.form else None
    result = user_mc.mediaUpdate(media_id, {'url': url, 'name': name, 'editor_notes': editor_notes,
        'is_monitored': monitored, 'public_notes': public_notes})
    # now we need to update the collections separately, because they are tags on the media source
    source = user_mc.media(media_id)
    existing_tag_ids = [t['tags_id'] for t in source['media_source_tags']
                        if (t['tag_sets_id'] in VALID_COLLECTION_TAG_SETS_IDS)]
    tag_ids_to_add = tag_ids_from_collections_param()
    tag_ids_to_remove = list(set(existing_tag_ids) - set(tag_ids_to_add))
    tags_to_add = [MediaTag(media_id, tags_id=cid, action=TAG_ACTION_ADD)
                   for cid in tag_ids_to_add if cid not in existing_tag_ids]
    tags_to_remove = [MediaTag(media_id, tags_id=cid, action=TAG_ACTION_REMOVE) for cid in tag_ids_to_remove]
    tags = tags_to_add + tags_to_remove
    if len(tags) > 0:   # don't make extraneous calls
        user_mc.tagMedia(tags=tags)
    # now update the metadata too
    valid_metadata = [
        {'form_key': 'publicationCountry', 'tag_sets_id': TAG_SETS_ID_PUBLICATION_COUNTRY},
        {'form_key': 'publicationState', 'tag_sets_id': TAG_SETS_ID_PUBLICATION_STATE},
        {'form_key': 'primaryLanguage', 'tag_sets_id': TAG_SETS_ID_PRIMARY_LANGUAGE},
        {'form_key': 'countryOfFocus', 'tag_sets_id': TAG_SETS_ID_COUNTRY_OF_FOCUS},
        {'form_key': 'mediaType', 'tag_sets_id': TAG_SETS_ID_MEDIA_TYPE}
    ]
    for metadata_item in valid_metadata:
        metadata_tag_id = request.form[metadata_item['form_key']] if metadata_item['form_key'] in request.form else None # this is optional
        existing_tag_ids = [t for t in source['media_source_tags'] if is_metadata_tag_set(t['tag_sets_id'])]
        # form field check
        if metadata_tag_id in [None, '', 'null', 'undefined']: