void indent(Indenter indenter) {
indenter.println(branch.data);
indenter.indent();
for (Node child : children) {
child.indent(indenter);
}
indenter.deindent();
}
void indent(Indenter indenter) {
indenter.println(this);
}
public String toString() {
Indenter indenter = new Indenter();
indent(indenter);
return indenter.toString();
}