What dessert is the apple behind of?
The apple is behind the cake.
   src        edge_attr  dst
0    0               of    1
1    1      in front of    4
2    1  to the right of    3
3    1      in front of    2
4    2           behind    1
5    3               of    1
6    3   to the left of    1
7    4           behind    1