How long is the tail?
The tail is short.
    src        edge_attr  dst
0     0  to the right of    6
1     0  to the right of    2
2     0  to the right of   13
3     2   to the left of    0
4     3   to the left of    5
5     3   to the left of   10
6     4   to the left of    5
7     4               in    5
8     4   to the left of   10
9     5  to the right of    4
10    5  to the right of    3
11    6  to the right of    7
12    6   to the left of    0
13    6   to the left of   11
14    6   to the left of    8
15    6       walking on   12
16    7   to the left of    6
17    8  to the right of    6
18    8  to the right of   13
19   10  to the right of    4
20   10  to the right of    3
21   11  to the right of   13
22   11  to the right of    6
23   11   to the left of   19
24   13   to the left of    0
25   13   to the left of    8
26   13   to the left of   11
27   16  to the right of   20
28   17               of   18
29   19  to the right of   11
30   20   to the left of   16