sub distance {
    ...
    do { return $1 + distance($_) if s/\(#:(\d+)\)/#/ }
    until ...
    ...
}

##</code><code>##

sub butter {
    my $_ = shift;
    return $1 + butter($_) if s/(\d+)//;
    return 0;
}

print butter 'effect / 7ACV06';