code: def update_rtc_as_set(self):
          
          # Compute the diffs in RTC_ASes
          curr_rtc_as_set = self._neighbors_conf.rtc_as_set
          # Always add local AS to RTC AS set
          curr_rtc_as_set.add(self._core_service.asn)
          removed_rtc_as_set = self._all_rtc_as_set - curr_rtc_as_set
          new_rtc_as_set = curr_rtc_as_set - self._all_rtc_as_set
  
          # Update to new RTC_AS set
          self._all_rtc_as_set = curr_rtc_as_set
  
          # Sync RT NLRI by adding/withdrawing as appropriate
          for new_rtc_as in new_rtc_as_set:
              for import_rt in self._all_vrfs_import_rts_set:
                  self._add_rt_nlri_for_as(new_rtc_as, import_rt)
          for removed_rtc_as in removed_rtc_as_set:
              for import_rt in self._all_vrfs_import_rts_set:
                  self._add_rt_nlri_for_as(removed_rtc_as, import_rt,
                                           is_withdraw=True)
docs: Syncs RT NLRIs for new and removed RTC_ASes.
  
          This method should be called when a neighbor is added or removed.