my @tokens = split '', $ARGV[0];

my %meta = (
    't' => \&time,
    'l' => \&log_level,
    'm' => \&message,
);

my $max_iter = scalar @tokens;

TOKEN:
while ($indx < $max_iter) {

    if ($tokens[$indx] eq '%') {
        $indx++;

        for my $key (keys %meta) {
            if ($tokens[$indx] eq $key) {
                $output = $output . &{ $meta{$key} };
                next TOKEN;
            }
        }
        $output = $output . '%' . $tokens[$indx];
        next TOKEN;
    }
    $output = $output . $tokens[$indx];
}
continue {
    $indx++;
}

print "\n$output\n";

##</code><code>##

$format =~ s/(%m)/&message()/;