@@ 158,6 158,7 @@ define : range-end-< a b
          cdr : range-start-end b
 
 define : merge-ranges received-ranges
+    ;; TODO: Add ranges that can have offsets, so bytevectors can be shared.
     ;; FIXME: this is currently too slow. First calculate the
     ;; resulting ranges with source-ranges, then create new
     ;; bytevectors and fill them without intermediate steps.