Is the fence made of wood or brick?
The fence is made of wood.
   src        edge_attr  dst
0    0   to the left of    5
1    1           behind    3
2    2   to the left of   15
3    2   to the left of    9
4    3      in front of    1
5    5  to the right of    0
6    9  to the right of    2
7   15  to the right of    2