What is covered in trees?
The hill is covered in trees.
    src        edge_attr  dst
0     0   to the left of   12
1     0   to the left of    3
2     1  to the right of   12
3     1  to the right of   10
4     3               in    8
5     3   to the left of   12
6     3  to the right of    0
7     4  to the right of   17
8     4  to the right of   16
9     4   to the left of   15
10    4   to the left of   21
11    5       covered in    1
12    6   to the left of   11
13    6   to the left of    9
14    7               in    8
15    9  to the right of    6
16   10   to the left of    1
17   11  to the right of    6
18   12   to the left of    1
19   12  to the right of    0
20   12  to the right of    3
21   14  to the right of   21
22   15  to the right of    4
23   15  to the right of   21
24   16   to the left of    4
25   16   to the left of   21
26   16   to the left of   23
27   17   to the left of   21
28   17   to the left of    4
29   18  to the right of   19
30   18  to the right of   20
31   19   to the left of   18
32   19  to the right of   20
33   20   to the left of   18
34   20   to the left of   19
35   21  to the right of   23
36   21   to the left of   15
37   21  to the right of   16
38   21  to the right of   22
39   21   to the left of   14
40   21  to the right of    4
41   21  to the right of   17
42   22   to the left of   21
43   23   to the left of   21
44   23  to the right of   16