code: async def _close(self):
          
  
          # Remove the core NATS Streaming subscriptions.
          try:
              if self._hb_inbox_sid is not None:
                  await self._nc.unsubscribe(self._hb_inbox_sid)
                  self._hb_inbox = None
                  self._hb_inbox_sid = None
              if self._ack_subject_sid is not None:
                  await self._nc.unsubscribe(self._ack_subject_sid)
                  self._ack_subject = None
                  self._ack_subject_sid = None
          except:
              # FIXME: async error in case these fail?
              pass
  
          # Remove all the related subscriptions
          for _, sub in self._sub_map.items():
              if sub._msgs_task is not None:
                  sub._msgs_task.cancel()
              try:
                  await self._nc.unsubscribe(sub.sid)
              except:
                  continue
          self._sub_map = {}
docs: Removes any present internal state from the client.