The trees are where?
The trees are on the forest.
    src        edge_attr  dst
0     0  to the right of   14
1     1   to the left of   10
2     1  to the right of   13
3     3  to the right of    7
4     3  to the right of   11
5     4  to the right of   13
6     5  to the right of    8
7     5  to the right of   10
8     6               on    7
9     7   to the left of    3
10    8   to the left of   14
11    8   to the left of    5
12    9  to the right of   11
13   10  to the right of    1
14   10   to the left of    5
15   11   to the left of    9
16   11   to the left of    3
17   13   to the left of    4
18   13   to the left of    1
19   14  to the right of    8
20   14   to the left of    0