sub compatible {
    my ($s1, $s2) = @_;
    my $t;
    $s1=~/\G_/gcs and $s2=~/./gcs or
        $s1=~/(.)/gcs and $t = $1, $s2=~/\G_/gcs or $s2=~/(.)/gcs and $t eq $1 or
        return 0 until
        $s1=~/\G\z/ or $s2=~/\G\z/;
    1;
}

printf "%s v %s ? %s\n", @$_, compatible( @$_ ) ? 1 : 0
        for [ qw[ _8__3__19 48____7__ ] ],  # compat
                [ qw[ _8__3__19 4_8___7__ ] ],  # compat
                [ qw[ _8__3__19 48_____7_ ] ];  # clash