code: async def get_txn(self, seq_no: int) -> str:
          
  
          LOGGER.debug('BaseAnchor.get_txn >>> seq_no: %s', seq_no)
  
          rv_json = json.dumps({})
          req_json = await ledger.build_get_txn_request(self.did, None, seq_no)
          resp = json.loads(await self._submit(req_json))
  
          rv_json = self.pool.protocol.txn2data(resp)
  
          LOGGER.debug('BaseAnchor.get_txn <<< %s', rv_json)
          return rv_json
docs: Find a transaction on the distributed ledger by its sequence number.
  
          :param seq_no: transaction number
          :return: json sequence number of transaction, null for no match