code: def _merge_objects(tref, merged, obj):
      
      size = None
      for (timestamp, tsize) in obj.snapshots:
          if timestamp == tref:
              size = tsize
      if size:
          _merge_asized(merged, size)
docs: Merge the snapshot size information of multiple tracked objects.  The
      tracked object `obj` is scanned for size information at time `tref`.
      The sizes are merged into **Asized** instance `merged`.