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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 cancel_reason(self, cancel_reason):
 """ Sets the cancel_reason of this OrderFulfillmentPickupDetails. A description of why the pickup was canceled. Max length is 100 characters. :param cancel_reason: The cancel_reason of this OrderFulfillmentPickupDetails. :type: str """


        if cancel_reason is None:
            raise ValueError("Invalid value for `cancel_reason`, must not be `None`")
        if len(cancel_reason) > 100:
            raise ValueError("Invalid value for `cancel_reason`, length must be less than `100`")

        self._cancel_reason = cancel_reason