use warnings;
use strict;
use Tree::Simple;

my $tree = Tree::Simple->new("0", Tree::Simple->ROOT);

while(<DATA>) {
    chomp;
    my ($child, $parent) = split ":";

    my $sub_tree = Tree::Simple->new("$parent", $tree);

    $sub_tree->addChild(Tree::Simple->new("$child"));

$tree->DESTROY();

}

$tree->traverse(sub {
    my ($_tree) = @_;
    print (("\t" x $_tree->getDepth()), $_tree->getNodeValue(), "\n");
});


__DATA__
apple:fruit
granny smith:apple
rotten granny smith:granny smith
orange:fruit