SV* get_parent(SV* obj) {
   Node *node = (Node *)SvIV(SvRV(obj));
   if(node != NULL && node->parent != NULL)
      return new(
         "Node", 
         node->parent->name,
         node->parent->desc,
         node->parent->branch_length
     );
   else 
      return NULL; // not sure
}