Find all the indexes (primary keys) based on the meta data

def meta_to_indexes(meta, table_name=None, model_name=None):
    """Find all the indexes (primary keys) based on the meta data 
    """
    indexes, pk_field = {}, None

    indexes = []
    for meta_model_name, model_meta in meta.iteritems():
        if (table_name or model_name) and not (table_name == model_meta['Meta'].get('db_table', '') or model_name == meta_model_name):
            continue
        field_name, field_infodict, score = find_index(model_meta)
        indexes.append(('%s.%s' % (meta_model_name, field_name), field_infodict, score))
    return indexes