DiGraph
                    Incoming  ( )  Outgoing
                                   (1), 2, 3,
                            1, 6,(2), 4,
                        1, 5, 6,(3), 4,
                            2, 3,(4), 8,10,
                                   (5), 3, 6,11,
                                5,(6), 2, 3, 8,11,
                                   (7),
                       4, 6,11,(8),12,
                                   (9),
                               4,(10),
                           5, 6,(11), 8,12,
                          8,11,(12),

Total degrees for each node:
(1)2 (2)3 (3)4 (4)4 (5)3 (6)5 (7)0 (8)4 (9)0 (10)1 (11)4 (12)2