Thanx go to:

* Mark Fowler, whose Perl Advent Calendar pages told me about Devel::Size.
* Dan Sugalski, the author of Devel::Size.
* SADAHIRO Tomoyuki for explaining the \\0 trick.
* Yves (demerphq) for the trick recording only nec. things in %SEEN:
  http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2005-02/msg00403.html
* Jim Cromie for spotting "indend" - Ouch! :)