Which color is the tail?
The tail is blue.
    src        edge_attr  dst
0     1  to the right of    8
1     1  to the right of    5
2     1  to the right of   12
3     3   to the left of   12
4     5  to the right of   12
5     5   to the left of    1
6     5  to the right of    6
7     6   to the left of    5
8     6   to the left of    8
9     6   to the left of   12
10    7   to the left of   10
11    8   to the left of    1
12    8  to the right of    6
13    8  to the right of   12
14   10  to the right of    7
15   12   to the left of    5
16   12  to the right of    3
17   12   to the left of    1
18   12   to the left of    8
19   12  to the right of    6