code: def get_disk_usage(self, path=None):
          
          DiskUsage = namedtuple('usage', 'total, used, free')
          if path is None:
              mount_point = self.mount_points[self.root.name]
          else:
              mount_point = self._mount_point_for_path(path)
          if mount_point and mount_point['total_size'] is not None:
              return DiskUsage(mount_point['total_size'],
                               mount_point['used_size'],
                               mount_point['total_size'] -
                               mount_point['used_size'])
          return DiskUsage(
              1024 * 1024 * 1024 * 1024, 0, 1024 * 1024 * 1024 * 1024)
docs: Return the total, used and free disk space in bytes as named tuple,
          or placeholder values simulating unlimited space if not set.
  
          .. note:: This matches the return value of shutil.disk_usage().
  
          Args:
              path: The disk space is returned for the file system device where
                  `path` resides.
                  Defaults to the root path (e.g. '/' on Unix systems).