$ ./1.1.nary.pl 
0 (depth 0) :i am the tree holding your categories id=0 parent=<noparent>
   1 (depth 1) :my id is 1 - at level 0 id=1 parent=0
      1.1 (depth 2) :my id is 1.1 - at level 1 id=1.1 parent=1
         1.1.1 (depth 3) :my id is 1.1.1 - at level 2 id=1.1.1 parent=1.1
         1.1.2 (depth 3) :my id is 1.1.2 - at level 2 id=1.1.2 parent=1.1
      1.2 (depth 2) :my id is 1.2 - at level 1 id=1.2 parent=1
         1.2.1 (depth 3) :my id is 1.2.1 - at level 2 id=1.2.1 parent=1.2
         1.2.2 (depth 3) :my id is 1.2.2 - at level 2 id=1.2.2 parent=1.2
   2 (depth 1) :my id is 2 - at level 0 id=2 parent=0
      2.1 (depth 2) :my id is 2.1 - at level 1 id=2.1 parent=2
         2.1.1 (depth 3) :my id is 2.1.1 - at level 2 id=2.1.1 parent=2.1
         2.1.2 (depth 3) :my id is 2.1.2 - at level 2 id=2.1.2 parent=2.1
      2.2 (depth 2) :my id is 2.2 - at level 1 id=2.2 parent=2
         2.2.1 (depth 3) :my id is 2.2.1 - at level 2 id=2.2.1 parent=2.2
         2.2.2 (depth 3) :my id is 2.2.2 - at level 2 id=2.2.2 parent=2.2


The """last""" category is....
         1.1.1 (depth 3) :my id is 1.1.1 - at level 2 id=1.1.1 parent=1.1
         1.1.2 (depth 3) :my id is 1.1.2 - at level 2 id=1.1.2 parent=1.1
         1.2.1 (depth 3) :my id is 1.2.1 - at level 2 id=1.2.1 parent=1.2
         1.2.2 (depth 3) :my id is 1.2.2 - at level 2 id=1.2.2 parent=1.2
         2.1.1 (depth 3) :my id is 2.1.1 - at level 2 id=2.1.1 parent=2.1
         2.1.2 (depth 3) :my id is 2.1.2 - at level 2 id=2.1.2 parent=2.1
         2.2.1 (depth 3) :my id is 2.2.1 - at level 2 id=2.2.1 parent=2.2
         2.2.2 (depth 3) :my id is 2.2.2 - at level 2 id=2.2.2 parent=2.2
Inserting a new node with id 2.1.20, under '2.1'...
0 (depth 0) :i am the tree holding your categories id=0 parent=<noparent>
   1 (depth 1) :my id is 1 - at level 0 id=1 parent=0
      1.1 (depth 2) :my id is 1.1 - at level 1 id=1.1 parent=1
         1.1.1 (depth 3) :my id is 1.1.1 - at level 2 id=1.1.1 parent=1.1
         1.1.2 (depth 3) :my id is 1.1.2 - at level 2 id=1.1.2 parent=1.1
      1.2 (depth 2) :my id is 1.2 - at level 1 id=1.2 parent=1
         1.2.1 (depth 3) :my id is 1.2.1 - at level 2 id=1.2.1 parent=1.2
         1.2.2 (depth 3) :my id is 1.2.2 - at level 2 id=1.2.2 parent=1.2
   2 (depth 1) :my id is 2 - at level 0 id=2 parent=0
      2.1 (depth 2) :my id is 2.1 - at level 1 id=2.1 parent=2
         2.1.1 (depth 3) :my id is 2.1.1 - at level 2 id=2.1.1 parent=2.1
         2.1.2 (depth 3) :my id is 2.1.2 - at level 2 id=2.1.2 parent=2.1
         2.1.20 (depth 3) :new inserted node id=2.1.20 parent=2.1
      2.2 (depth 2) :my id is 2.2 - at level 1 id=2.2 parent=2
         2.2.1 (depth 3) :my id is 2.2.1 - at level 2 id=2.2.1 parent=2.2
         2.2.2 (depth 3) :my id is 2.2.2 - at level 2 id=2.2.2 parent=2.2
$