sub arrays_eq (\@\@) {
  my ($a1, $a2) = @_;
  # Same length?
  return 0 unless @$a1 == @$a2;
  # Same contents?
  for (0..$#$a1) {
    return 0 if $a1->[$_] ne $a2->[$_];
  }
  return 1;
}