#! perl -slw
use strict;
use Data::Dump qw[ pp ];

sub genNested {
    my $n = shift;
    map{ rand() < 0.5 ? [ rand(1000), genNested( $n-1 ) ] : rand( 1000 ) } 1 .. $n;
}

sub genIterator {
    my $tree = shift;
    my @stack = [ $tree, 0 ];
    return sub {
        ## Fill in the blank (please :).
    }
}

my @nested = genNested( 3 );
pp \@nested;

my $iter = genIterator( \@nested );

while( my $next = $iter->() ) {
    last if $next == $something;
    ## do stuff with $next.
}