Is there any flag on the post?
Yes, there is a flag on the post.
    src        edge_attr  dst
0     0       hanging on    2
1     0  to the right of    5
2     1  to the right of    8
3     1  to the right of   11
4     1  to the right of    9
5     5  to the right of    6
6     5   to the left of    0
7     5   to the left of   10
8     5  to the right of    7
9     5               on    2
10    6   to the left of    5
11    7               on    6
12    7   to the left of    5
13    8   to the left of   12
14    8   to the left of    1
15    9   to the left of    1
16    9   to the left of   13
17   10  to the right of    5
18   11               in    9
19   11   to the left of   12
20   11   to the left of    1
21   12  to the right of   11
22   12   to the left of   13
23   12               on    1
24   12  to the right of    8
25   13  to the right of   12
26   13  to the right of    9