code: def create_fork_relation(self, forked_from_id, **kwargs):
          
          path = '/projects/%s/fork/%s' % (self.get_id(), forked_from_id)
          self.manager.gitlab.http_post(path, **kwargs)
docs: Create a forked from/to relation between existing projects.
  
          Args:
              forked_from_id (int): The ID of the project that was forked from
              **kwargs: Extra options to send to the server (e.g. sudo)
  
          Raises:
              GitlabAuthenticationError: If authentication is not correct
              GitlabCreateError: If the relation could not be created