What sign is octagonal?
The sign is a street sign.
    src        edge_attr  dst
0     0  to the right of    8
1     0  to the right of    7
2     0   to the left of    5
3     1               on    7
4     3               on    7
5     4               on    7
6     5  to the right of    8
7     5  to the right of    0
8     7   to the left of    0
9     8   to the left of    0
10    8   to the left of    5
11    8               on    7