What are the birds sitting on?
The birds are sitting on the traffic signal.
    src        edge_attr  dst
0     0       sitting on    4
1     0  to the right of    4
2     0               on    6
3     1            below    3
4     2             near    4
5     2            below    3
6     4             near    2
7     4   to the left of    0
8     4   to the left of    6
9     5               on    2
10    6  to the right of    4