code: def cancelMktDepth(self, contract: Contract, isSmartDepth=False):
          
          ticker = self.ticker(contract)
          reqId = self.wrapper.endTicker(ticker, 'mktDepth')
          if reqId:
              self.client.cancelMktDepth(reqId, isSmartDepth)
          else:
              self._logger.error(
                  f'cancelMktDepth: No reqId found for contract {contract}')
docs: Unsubscribe from market depth data.
  
          Args:
              contract: The exact contract object that was used to
                  subscribe with.