code: def garbage_graph(index):
      
      graph = _compute_garbage_graphs()[int(index)]
      reduce_graph = bottle.request.GET.get('reduce', '')
      if reduce_graph:
          graph = graph.reduce_to_cycles()
      if not graph:
          return None
      filename = 'garbage%so%s.png' % (index, reduce_graph)
      rendered_file = _get_graph(graph, filename)
      if rendered_file:
          bottle.send_file(rendered_file, root=server.tmpdir)
      else:
          return None
docs: Get graph representation of reference cycle.