Granting permission for users to create users...

Novice PostgreSQL,

I'm trying to create a user who can create other users and grant
permissions to them.  The manual states this should work:

grant all on {object} to {user} with grant option;

But the reply I get is:

ERROR:  grant options are not implemented

How do I create a user with permissions to user the 'grant' option?

Regards,
Ben