private void dfsgt_visit(TypeVariableBV var) {
current_tree.add(var);
BitVector children = var.children();
for (BitSetIterator i = children.iterator(); i.hasNext(); ) {
TypeVariableBV child = resolver.typeVariableForId(i.next());
if (!black.contains(child)) {
black.add(child);
dfsgt_visit(child);
}
}
}