# File lib/treetop/runtime/syntax_node.rb, line 93
      def write_dot(io)
        io.puts "node#{dot_id} [label=\"'#{text_value}'\"];"
        if nonterminal? then
          elements.each do
            |x|
            io.puts "node#{dot_id} -> node#{x.dot_id};"
            x.write_dot(io)
          end
        end
      end