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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 _write_log(self):
 """ Write log info """

        logger.info("Writing config file %s" % self.path)

        if settings.DEBUG:
            try:
                old_content = open(self.path, 'r').readlines()
            except IOError:
                old_content = ''

            new_content = self.contents().splitlines(True)
            diff = difflib.unified_diff(old_content, new_content,
                                        fromfile=self.path, tofile=self.path)
            if diff:
                logger.debug('Diff:\n' + ''.join(diff))
            else:
                logger.debug('File not changed')