What is on the rocks?
The moss is on the rocks.
    src        edge_attr  dst
0     0   to the left of    1
1     0   to the left of    6
2     1               on    6
3     1  to the right of    0
4     1   to the left of    6
5     1  to the right of    4
6     2   to the left of    5
7     4   to the left of    1
8     4   to the left of    9
9     4   to the left of    6
10    5  to the right of    8
11    5       growing on    3
12    5  to the right of    2
13    5  to the right of    7
14    6  to the right of    0
15    6  to the right of    1
16    6  to the right of    4
17    7   to the left of    5
18    8   to the left of    5
19    9  to the right of    4