Helper method for `get_favorite_radio_*` methods.

        Args:
            favorite_type (str): Specify either `RADIO_STATIONS` or
                `RADIO_SHOWS`.
            start (int): Which number to start the retrieval from. Used for
                paging.
            max_items (int): The total number of results to return.

def __get_favorites(self, favorite_type, start=0, max_items=100):
        """ Helper method for `get_favorite_radio_*` methods.

        Args:
            favorite_type (str): Specify either `RADIO_STATIONS` or
                `RADIO_SHOWS`.
            start (int): Which number to start the retrieval from. Used for
                paging.
            max_items (int): The total number of results to return.

        """
        if favorite_type not in (RADIO_SHOWS, RADIO_STATIONS):
            favorite_type = SONOS_FAVORITES

        response = self.contentDirectory.Browse([
            ('ObjectID',
             'FV:2' if favorite_type is SONOS_FAVORITES
             else 'R:0/{0}'.format(favorite_type)),
            ('BrowseFlag', 'BrowseDirectChildren'),
            ('Filter', '*'),
            ('StartingIndex', start),
            ('RequestedCount', max_items),
            ('SortCriteria', '')
        ])
        result = {}
        favorites = []
        results_xml = response['Result']

        if results_xml != '':
            # Favorites are returned in DIDL-Lite format
            metadata = XML.fromstring(really_utf8(results_xml))

            for item in metadata.findall(
                    '{urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/}container'
                    if favorite_type == RADIO_SHOWS else
                    '{urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/}item'):
                favorite = {}
                favorite['title'] = item.findtext(
                    '{http://purl.org/dc/elements/1.1/}title')
                favorite['uri'] = item.findtext(
                    '{urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/}res')
                if favorite_type == SONOS_FAVORITES:
                    favorite['meta'] = item.findtext(
                        '{urn:schemas-rinconnetworks-com:metadata-1-0/}resMD')
                favorites.append(favorite)

        result['total'] = response['TotalMatches']
        result['returned'] = len(favorites)
        result['favorites'] = favorites

        return result