How do i set Expires, and cache control Headers

[ashokrkm]

How do i set Expires, and cache control Headers?
This doesn't set the expires and cache control headers.

    sl_storage = object_storage.get_client('XXX', 'YYY',datacenter='sjc01')
    f=sl_storage['video']['aa.txt'].create()
    f.load_from_filename('aa.txt')
    f.update(headers={'Expires':'Thu, 31 Dec 2037 23:55:55 GMT', 'Cache-Control':'public'})

Headers are not set.

    curl -I https://sjc01.objectstorage.softlayer.net/v1/AUTH_e3f9614e-c713-4151-a633-45d4a4d1381b/video/aa.txt
    HTTP/1.1 200 OK
    Content-Length: 8
    X-Backend-Timestamp: 1433976739.38300
    Accept-Ranges: bytes
    Last-Modified: Wed, 10 Jun 2015 22:52:20 GMT
    Etag: 93845a628143e88c97bae71e4cd4cbae
    X-Timestamp: 1433976739.38300
    Content-Type: text/plain
    X-Trans-Id: txe3e01937473d4386b540a-005578bfa9
    Date: Wed, 10 Jun 2015 22:52:25 GMT