def get_sort_on(allowed_indexes=None):
sort_on = get("<STR_LIT>")<EOL>if allowed_indexes and sort_on not in allowed_indexes:<EOL><INDENT>logger.warn("<STR_LIT>".format(sort_on))<EOL>return None<EOL><DEDENT>return sort_on<EOL>
returns the 'sort_on' from the request