Where are the trees?
The trees are on the mountain.
    src        edge_attr  dst
0     1  to the right of    4
1     2               on    4
2     4   to the left of    9
3     4   to the left of    7
4     4   to the left of   10
5     4   to the left of    1
6     6   to the left of    9
7     7  to the right of    4
8     8               on    5
9     9  to the right of    6
10    9  to the right of    4
11   10  to the right of    4
12   10               in    9
13   10        on top of    9