code: public void printDot(PrintStream os, int maxLevelsToPrintPerEdge, boolean detail, String optionalTitle, PrintMojo.PrintTreeOptions treeOptions) {
      os.println("/*");
      os.println("Generated by:");
      os.println("    http://https://github.com/h2oai/h2o-3/tree/master/h2o-genmodel/src/main/java/hex/genmodel/tools/PrintMojo.java");
      os.println("*/");
      os.println("");
      os.println("/*");
      os.println("On a mac:");
      os.println("");
      os.println("$ brew install graphviz");
      os.println("$ dot -Tpng file.gv -o file.png");
      os.println("$ open file.png");
      os.println("*/");
      os.println("");
      os.println("digraph G {");
      for (SharedTreeSubgraph sg : subgraphArray) {
        sg.printDot(os, maxLevelsToPrintPerEdge, detail, optionalTitle, treeOptions);
      }
      os.println("");
      os.println("}");
      os.println("");
    }
docs: Print graph output in a format readable by dot (graphviz).
  @param os Stream to write the output to
  @param maxLevelsToPrintPerEdge Limit the number of individual categorical level names printed per edge
  @param detail include addtional node detail information
  @param optionalTitle Optional title to override the default
  @param treeOptions object of PrintTreeOptions to control how trees are printed in terms of font size and number of decimal places for numerical values