public String print(String tab) { return tab + "type = " + type + Out.NL + tab + "child 1 :" + Out.NL + //$NON-NLS-1$ //$NON-NLS-2$ r1.print(tab + " ") + Out.NL + tab + "child 2 :" + Out.NL + //$NON-NLS-1$ //$NON-NLS-2$ r2.print(tab + " "); // $NON-NLS-1$ }