What's on the tree?
The moss is on the tree.
   src        edge_attr  dst
0    0  to the right of    3
1    0  to the right of    2
2    0      in front of    5
3    2   to the left of    0
4    3   to the left of    4
5    3               on    1
6    3   to the left of    0
7    4  to the right of    3
8    4               on    0
9    5           behind    0