As Simon Cozens points out in Where Wizards Fear To Tread, Acme::Don't doesn't support double negatives either. The following code doesn't print anything.

my $x = 1;
don't { print "Something\n" } unless $x;
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I don't see it as being at all useful, but I doubt it was intended to be used at all :). However, I can think of a few good uses for Acme::Bleach. If I can just remember where Matt's script archive is... ;-).