# File lib/kwala/lib/cycle_detector.rb, line 499
    def print_ml_wrapper(&block)
      @visited.clear

      puts "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
      puts "<graphml xmlns=\"http://graphml.graphdrawing.org/xmlns\">"
      puts "<graph edgedefault=\"directed\">"
      puts "<!-- data schema -->"
      puts "<key id=\"name\" for=\"node\" attr.name=\"name\" attr.type=\"string\"/>"

      yield

      puts "</graph>"
      puts "</graphml>"

      @visited.clear
      @edges = []
      @cid = 0
      @nodeid.clear
    end