What kind of vegetable is on the plate?
The vegetable is a lemon.
   src        edge_attr  dst
0    0   to the left of    1
1    1               on    2
2    1   to the left of    3
3    1  to the right of    0
4    2               on    0
5    3               on    2
6    3  to the right of    1
7    4               on    2
8    4               on    0