use File::Find;
my $TOP = "/some/place/out/there";
my %sums;
find sub {
  my @places = split qr{/}, $File::Find::name;
  my $blocks = (stat($_))[12];
  while (@places) {
    $sums{join "/", @places} += $blocks;
    pop @places;
  }
}, $TOP;
# now $sums{"/some/place/out/there/foo"} contains the aggregate sum of
+ all blocks below that directory!
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