sub this {
  my (undef, $href, $field, $depth, $flat_rec) = @_;

  @flattened = () unless defined($depth);

  if (ref $href) {
    my @key = keys %$href;
#    warn "ref $href succeeded. depth: $depth keys: @key, the ref:", Dumper($hre\
f);
    for my $key_i (0..$#key) {

      my $key = $key[$key_i];

#      warn "KEY: $key";
      $flat_rec->{$field->[$depth]} = $key;
#      warn "(depth $depth) flat_rec->{$field->[$depth]} = $key";

      Data::Hash::Flatten->this($href->{$key}, $field, $depth+1, $flat_rec, @fla\
ttened);
    }
  } else {

    $flat_rec->{$field->[$depth]} = $href;

#    warn "no more refs. we are at bottom. pushing:", Dumper($flat_rec), "here i\
s href:", Dumper($href), "depth $depth";
    use Storable qw(dclone);

    my $new_rec = dclone $flat_rec;
    push @flattened, $new_rec;
  }
 @flattened;
}