code: def list_roles_for_user(self, user):
          
          user_id = utils.get_id(user)
          uri = "users/%s/roles" % user_id
          resp, resp_body = self.method_get(uri)
          if resp.status_code in (401, 403):
              raise exc.AuthorizationFailure("You are not authorized to list "
                      "user roles.")
          roles = resp_body.get("roles")
          return roles
docs: ADMIN ONLY. Returns a list of roles for the specified user. Each role
          will be a 3-tuple, consisting of (role_id, role_name,
          role_description).