'Builds up the path to a poster thumb cache for a given Indexer ID
:param indexer_id: ID of the show to use in the file name
:return: a full path to the cached poster thumb file for the given Indexer ID'

def poster_thumb_path(self, indexer_id):

    posterthumb_file_name = (str(indexer_id) + u'.poster.jpg')
    return ek(os.path.join, self._thumbnails_dir(), posterthumb_file_name)
