def get_s3item_md5(item):
    """
    A remote item's md5 may or may not be available, depending on whether or
    not it was been downloaded. If a download hasn't occurred, the checksum
    can be fetched using the files HTTP ETag.
    """
    if item.md5 is not None:
        return item.md5
    else:
        # Remove ETAG with any quotes removed:
        return item.etag.replace('"','').replace("'","")