code: func (v *TreeModel) IterChildren(iter, child *TreeIter) bool {
  	var cIter, cChild *C.GtkTreeIter
  	if iter != nil {
  		cIter = iter.native()
  	}
  	cChild = child.native()
  	c := C.gtk_tree_model_iter_children(v.native(), cChild, cIter)
  	return gobool(c)
  }
docs: // IterChildren is a wrapper around gtk_tree_model_iter_children().