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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def garbage_graph(index):
 """Get graph representation of reference cycle."""

    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