What does the moss grow on?
The moss grows on the tree.
    src        edge_attr  dst
0     0               of    4
1     0   to the left of    9
2     1  to the right of   10
3     1  to the right of   13
4     1  to the right of    7
5     1  to the right of    9
6     3   to the left of    4
7     3   to the left of    7
8     3   to the left of   10
9     3   to the left of   13
10    4  to the right of    7
11    4  to the right of    8
12    4  to the right of   13
13    4  to the right of   10
14    4  to the right of    3
15    5               on    1
16    5  to the right of    9
17    7  to the right of    8
18    7   to the left of    4
19    7  to the right of    3
20    7   to the left of    9
21    7   to the left of    1
22    8   to the left of    7
23    8   to the left of    4
24    8   to the left of   10
25    9   to the left of    1
26    9               of    4
27    9   to the left of    5
28    9  to the right of    7
29    9  to the right of   10
30    9  to the right of    0
31   10  to the right of    8
32   10   to the left of    1
33   10   to the left of    9
34   10  to the right of    3
35   10   to the left of    4
36   10     growing near    2
37   10     growing near    6
38   13       growing on   10
39   13   to the left of    1
40   13  to the right of    3
41   13   to the left of    4