Version 4 UUIDs.
[ being those with bits 48-52 set to 0100 and bits 64-66 set to 10 ].
This uses python 2.7's os.urandom ( on GAE ).
Change /16 to /64 to get a padded base64 encoded GUID/UUID.
In the seemingly unlikely event that this exceeds its free quota, it will become a for-pay API.