code: def update_all(self, rs=None, since=None):
          "Sync all objects for the relations rs (if None, sync all resources)"
          self._log.info("Updating resources: %s", ' '.join(r.tag for r in rs))
  
          if rs is None:
              rs = resource.all_resources()
          ctx = self._ContextClass(self)
          for r in rs:
              self._atomic_update(lambda: ctx.sync_resource(r, since=since)f update_all(self, rs=None, since=None):
          "Sync all objects for the relations rs (if None, sync all resources)"
          self._log.info("Updating resources: %s", ' '.join(r.tag for r in rs))
  
          if rs is None:
              rs = resource.all_resources()
          ctx = self._ContextClass(self)
          for r in rs:
              self._atomic_update(lambda: ctx.sync_resource(r, since=since))
docs: Sync all objects for the relations rs (if None, sync all resources)