c:\@Work\Perl\monks>perl -wMstrict -le
"use Data::Dumper;
 ;;
 my $sequence = 'ABCDEFG';
 print qq{sequence entered: '$sequence'};
 warn sprintf 'sequence length (%d) not multiple of 3', length($sequence)
   if length($sequence) % 3;
 ;;
 my @trips = unpack('a3' x (length($sequence)-2), $sequence);
 print Dumper \@trips;
 ;;
 @trips = unpack('(a3)*', $sequence);
 print Dumper \@trips;
"
sequence entered: 'ABCDEFG'
sequence length (7) not multiple of 3 at -e line 1.
$VAR1 = [
          'ABC',
          'DEF',
          'G',
          '',
          ''
        ];

$VAR1 = [
          'ABC',
          'DEF',
          'G'
        ];