import requests


def load_mta_archived_feed(feed='gtfs', timestamp='2014-09-17-09-31'):
    """
    Returns archived GTFS data for a particular time_assigned.

    Parameters
    ----------
    feed: {'gtfs', 'gtfs-l', 'gtfs-si'}
        Archival data is provided in these three rollups. The first one covers 1-6 and the S, 
        the second covers the L, and the third, the Staten Island Railway.
    timestamp: str
        The time_assigned associated with the data rollup. The files are time stamped at 01, 
        06, 11, 16, 21, 26, 31, 36, 41, 46, 51, and 56 minutes after the hour, so only these 
        times will be valid.
    """
    return requests.get(
        "https://datamine-history.s3.amazonaws.com/{0}-{1}".format(feed, timestamp)
    )