The tree consists of ontologies. any number of children is possible.
e.g. 
Building
  House
    Window
      Glas
        Silicium
    Door
    Roof
      Wood
  Hut
    Pizza
  Garage
    Door

##</code><code>##

the result should be 

$hash = { label =>'Building',
          children=>[
                       {label=>'House',
                        children=>[
                                    {label=>'Window',
                                     children=>[ ....
                                  ],
                        {
                          ...
                        },
                    ] 
         };