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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def cancelPnL(self, account, modelCode: str = ''):
 """ Cancel PnL subscription. Args: account: Cancel for this account. modelCode: If specified, cancel for this account model. """

        key = (account, modelCode)
        reqId = self.wrapper.pnlKey2ReqId.pop(key, None)
        if reqId:
            self.client.cancelPnL(reqId)
            self.wrapper.pnls.pop(reqId, None)
        else:
            self._logger.error(
                'cancelPnL: No subscription for '
                f'account {account}, modelCode {modelCode}')