'Remove user from a tenant.
:raises keystone.exception.ProjectNotFound: If the project doesn\'t
exist.
:raises keystone.exception.UserNotFound: If the user doesn\'t exist.'

def remove_user_from_project(self, tenant_id, user_id):

    roles = self.get_roles_for_user_and_project(user_id, tenant_id)
    if (not roles):
        raise exception.NotFound(tenant_id)
    for role_id in roles:
        try:
            self.driver.remove_role_from_user_and_project(user_id, tenant_id, role_id)
        except exception.RoleNotFound:
            LOG.debug('Removing    role    %s    failed    because    it    does    not    exist.', role_id)
    COMPUTED_ASSIGNMENTS_REGION.invalidate()
