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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 _report_disk_stats(self):
 """Report metrics about the volume space usage"""

        stats = {
            'docker.data.used': None,
            'docker.data.total': None,
            'docker.data.free': None,
            'docker.metadata.used': None,
            'docker.metadata.total': None,
            'docker.metadata.free': None
            # these two are calculated by _calc_percent_disk_stats
            # 'docker.data.percent': None,
            # 'docker.metadata.percent': None
        }
        info = self.docker_util.client.info()
        driver_status = info.get('DriverStatus', [])
        if not driver_status:
            self.log.warning('Disk metrics collection is enabled but docker info did not'
                             ' report any. Your storage driver might not support them, skipping.')
            return
        for metric in driver_status:
            # only consider metrics about disk space
            if len(metric) == 2 and 'Space' in metric[0]:
                # identify Data and Metadata metrics
                mtype = 'data'
                if 'Metadata' in metric[0]:
                    mtype = 'metadata'

                if 'Used' in metric[0]:
                    stats['docker.{0}.used'.format(mtype)] = metric[1]
                elif 'Space Total' in metric[0]:
                    stats['docker.{0}.total'.format(mtype)] = metric[1]
                elif 'Space Available' in metric[0]:
                    stats['docker.{0}.free'.format(mtype)] = metric[1]
        stats = self._format_disk_metrics(stats)
        stats.update(self._calc_percent_disk_stats(stats))
        tags = self._get_tags()
        for name, val in stats.iteritems():
            if val is not None:
                self.gauge(name, val, tags)