code: def add_user_role(self, user, role):
          
          self.service.add_user_role(
              user, role,
              self.url_prefix, self.auth, self.session, self.session_send_opts)
docs: Add role to given user.
  
          Args:
              user (string): User name.
              role (string): Role to assign.
  
          Raises:
              requests.HTTPError on failure.