gistfile1.py

    expires = datetime.utcnow() + timedelta(days=(25 * 365))
    expires = expires.strftime("%a, %d %b %Y %H:%M:%S GMT")
    file.seek(0)
    k.set_contents_from_string(file.read(), headers={
      'Content-Type': 'image/jpeg',
      'Cache-Control': 'public',
      'Expires': expires,
      })