code: def advise(self, item, stop=False):
          
          hszItem = DDE.CreateStringHandle(self._idInst, item, CP_WINUNICODE)
          hDdeData = DDE.ClientTransaction(LPBYTE(), 0, self._hConv, hszItem, CF_TEXT, XTYP_ADVSTOP if stop else XTYP_ADVSTART, TIMEOUT_ASYNC, LPDWORD())
          DDE.FreeStringHandle(self._idInst, hszItem)
          if not hDdeData:
              raise DDEError("Unable to %s advise" % ("stop" if stop else "start"), self._idInst)
          DDE.FreeDataHandle(hDdeData)
docs: Request updates when DDE data changes.