What's on the trees?
The snow is on the trees.
   src        edge_attr  dst
0    0   to the left of    5
1    2               on    4
2    4  to the right of    7
3    5  to the right of    0
4    6   to the left of    7
5    7               on    6
6    7   to the left of    4
7    7  to the right of    6