+ @staticmethod
+ def _merge_subtitle_items(subtitle_list1, subtitle_list2):
+ """ Merge subtitle items for one language. Items with duplicated URLs
+ will be dropped. """
+ list1_urls = set([item['url'] for item in subtitle_list1])
+ ret = list(subtitle_list1)
+ ret.extend([item for item in subtitle_list2 if item['url'] not in list1_urls])
+ return ret
+
+ @classmethod
+ def _merge_subtitles(cls, subtitle_dict1, subtitle_dict2):
+ """ Merge two subtitle dictionaries, language by language. """
+ ret = dict(subtitle_dict1)
+ for lang in subtitle_dict2:
+ ret[lang] = cls._merge_subtitle_items(subtitle_dict1.get(lang, []), subtitle_dict2[lang])
+ return ret
+