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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 _preprocess(self, message_in, measurement):
 """Invoked at the start of execution, setting internal state, validating that the message should be processed and not dropped. :param message_in: The message to process :type message_in: :class:`rejected.data.Message` :param measurement: For collecting per-message instrumentation :type measurement: :class:`rejected.data.Measurement` :raises: rejected.errors.MessageException :raises: rejected.errors.DropMessage """

        self._clear()
        self._message = message_in
        self._measurement = measurement

        self._maybe_set_message_age()

        # Ensure there is a correlation ID
        self._correlation_id = (
                self._message.properties.correlation_id or
                self._message.properties.message_id or
                str(uuid.uuid4()))

        # Set the Correlation ID for the connection for logging
        self._connections[self._message.connection].correlation_id = \
            self._correlation_id

        # Set the sentry context for the message type if set
        if self.message_type:
            self.set_sentry_context('type', self.message_type)

        # Validate the message type if validation is turned on
        if self._message_type:
            self._validate_message_type()

        # Check the number of ProcessingErrors and possibly drop the message
        if self._error_max_retry and _PROCESSING_EXCEPTIONS in self.headers:
            self._maybe_drop_message()