code: def add_group_maintainer(self, name, user):
          
          self.project_service.set_auth(self._token_project)
          self.project_service.add_group_maintainer(name, user)
docs: Add the given user to the named group.
  
          Both group and user must already exist for this to succeed.
  
          Args:
              name (string): Name of group.
              user (string): User to add to group.
  
          Raises:
              requests.HTTPError on failure.