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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 filter(self, record):
 """Is the specified record to be logged? Returns zero for no, nonzero for yes. If deemed appropriate, the record may be modified in-place by this method. :param logging.LogRecord record: The log record to process :rtype: int """

        if self._exists:
            return int(getattr(record, 'correlation_id', None) is not None)
        return int(getattr(record, 'correlation_id', None) is None)