use Mail::Cclient qw(set_callback);

my $thr = $cclient->thread(
			THREADING => "references",
			SEARCH    => "ALL FROM \"hdias\"",
			FLAG      => "uid");

# $thr = [214, [5, 12, 24], 144, 123, [5, [10, 8, 2]], 65]

&loop($thr, "");

sub loop {
    my ($thr, $str) = @_;

    for(@{$thr}) {
	if(ref($_) eq "ARRAY") {
	    &loop($_, $str . "--");
	} else {
	    print "$str> $_\n";
	}
    }
}

1;

> 214
--> 5
--> 12
--> 24
> 144
> 123
--> 5
----> 10
----> 8
----> 2
> 65