=head1 NAME
perlfilter - Source Filters
-
+
=head1 DESCRIPTION
C<decrypt> filter (which unscrambles the source before Perl parses it)
included with the source filter distribution is an example of a C
source filter (see Decryption Filters, below).
-
+
=over 5
package Debug;
use strict;
+ use warnings;
use Filter::Util::Call ;
use constant TRUE => 1 ;