@a = qw(a b);
@b = map { s/([ac])/uc $1/e } @a;
print join( ",", map {length($_) ? $_ : q{""}} @{$_} ), "\n"
  foreach \@a, \@b;

##</code><code>##

@mod_lines = map { (my $tmp = $_) =~ s/^#.*//; $tmp } @all_lines;