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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 firmware_checksum(self, firmware_checksum):
 """ Sets the firmware_checksum of this DeviceDataPostRequest. The SHA256 checksum of the current firmware image. :param firmware_checksum: The firmware_checksum of this DeviceDataPostRequest. :type: str """

        if firmware_checksum is not None and len(firmware_checksum) > 64:
            raise ValueError("Invalid value for `firmware_checksum`, length must be less than or equal to `64`")

        self._firmware_checksum = firmware_checksum