How tall are the bare trees?
The trees are short.
    src        edge_attr  dst
0     0   to the left of    6
1     1   to the left of   13
2     1  to the right of   10
3     1   to the left of    6
4     2   to the left of   13
5     3   to the left of   18
6     3  to the right of   10
7     4   to the left of    6
8     4   to the left of   12
9     6      in front of   10
10    6  to the right of    0
11    6  to the right of    4
12    6  to the right of    8
13    6  to the right of   18
14    6  to the right of   15
15    6   to the left of   13
16    6  to the right of    1
17    8   to the left of    6
18   10   to the left of    1
19   10   to the left of    3
20   11               on   17
21   11  to the right of   17
22   12  to the right of    4
23   13  to the right of    1
24   13  to the right of    2
25   13  to the right of    6
26   14               of    1
27   15   to the left of    6
28   17   to the left of   11
29   18   to the left of    6
30   18  to the right of    3