docs: def _link_or_update_vars(self):
          """
          Creates or updates the symlink to group_vars and returns None.
  
          :returns: None
          """
          for d, source in self.links.items():
              target = os.path.join(self.inventory_directory, d)
              source = os.path.join(self._config.scenario.directory, source)
  
              if not os.path.exists(source):
                  msg = "The source path '{}' does not exist.".format(source)
                  util.sysexit_with_message(msg)
              msg = "Inventory {} linked to {}".format(source, target)
              LOG.info(msg)
              os.symlink(source, target)