code: def register_system_role(self, system_role):
          
          assert system_role.value not in self.system_roles
          self.system_roles[system_role.value] = system_role
docs: Register a system role.
  
          .. note:: A system role can't be registered two times. If it happens,
          then an assert exception will be raised.
  
          :param system_role: The system role to be registered.