code: async def revoke(self, username, acl='login'):
          
          controller_facade = client.ControllerFacade.from_connection(
              self.connection())
          user = tag.user(username)
          changes = client.ModifyControllerAccess('login', 'revoke', user)
          return await controller_facade.ModifyControllerAccess([changes])
docs: Removes some or all access of a user to from a controller
          If 'login' access is revoked, the user will no longer have any
          permissions on the controller. Revoking a higher privilege from
          a user without that privilege will have no effect.
  
          :param str username: username
          :param str acl: Access to remove ('login', 'add-model' or 'superuser')