code: def rpc_get_subdomain_ops_at_txid(self, txid, **con_info):
          
          if not check_string(txid, min_length=64, max_length=64, pattern='^[0-9a-fA-F]{64}$'):
              return {'error': 'Not a valid txid', 'http_status': 400}
         
          subdomain_ops = get_subdomain_ops_at_txid(txid)
          return self.success_response( {'subdomain_ops': subdomain_ops} )
docs: Return the list of subdomain operations accepted within a given txid.
          Return {'status': True, 'subdomain_ops': [{...}]} on success
          Return {'error': ...} on error