code: def _nodemap_changed(self, data, stat):
          
  
          if not stat:
              raise EnvironmentNotFoundException(self.nodemap_path)
  
          try:
              conf_path = self._deserialize_nodemap(data)[self.hostname]
          except KeyError:
              conf_path = '/services/%s/conf' % self.service
  
          self.config_watcher = DataWatch(
              self.zk, conf_path,
              self._config_changed
          )
docs: Called when the nodemap changes.