code: static String toDot(Node n, ControlFlowGraph<Node> inCFG)
        throws IOException  {
      StringBuilder builder = new StringBuilder();
      new DotFormatter(n, inCFG, builder, false);
      return builder.toString();
    }
docs: Converts an AST to dot representation.
  @param n the root of the AST described in the dot formatted string
  @param inCFG Control Flow Graph.
  @return the dot representation of the AST