code: def get_subdomain_ops_at_txid(self, txid, cur=None):
          
          get_cmd = 'SELECT * FROM {} WHERE txid = ? ORDER BY zonefile_offset'.format(self.subdomain_table)
  
          cursor = None
          if cur is None:
              cursor = self.conn.cursor()
          else:
              cursor = cur
  
          db_query_execute(cursor, get_cmd, (txid,))
  
          try:
              return [x for x in cursor.fetchall()]
          except Exception as e:
              if BLOCKSTACK_DEBUG:
                  log.exception(e)
  
              return []
docs: Given a txid, get all subdomain operations at that txid.
          Include unaccepted operations.
          Order by zone file index