code: def dot_format(out, graph, name="digraph"):
      
  
      out.write("digraph %s {\n" % name)
      for step, deps in each_step(graph):
          for dep in deps:
              out.write("  \"%s\" -> \"%s\";\n" % (step, dep))
  
      out.write("}\n")
docs: Outputs the graph using the graphviz "dot" format.