def partition_key(self, value):
        """
        Set the partition key of the event data object.

        :param value: The partition key to set.
        :type value: str or bytes
        """
        annotations = dict(self._annotations)
        annotations[self._partition_key] = value
        header = MessageHeader()
        header.durable = True
        self.message.annotations = annotations
        self.message.header = header
        self._annotations = annotations
Set the partition key of the event data object.

        :param value: The partition key to set.
        :type value: str or bytes