def METHOD_NAME( nmirrors):
    h = nx.Graph()
    node_count = 1 + 2 * (1 + nmirrors)
    h.add_nodes_from( list(range(node_count)))
    device_offset = 1 + 1 + nmirrors
    # ref
    h.add_edges_from( [(0,device_offset), (1,device_offset)])
    # mirrors
    for i in range(nmirrors):
        h.add_edges_from( [(0,device_offset+1+i),(1,device_offset+1+i),(2+i,device_offset+1+i)])
    return h