What is the green grass surrounded by?
The grass is surrounded by the tree.
    src        edge_attr  dst
0     0           behind   14
1     0   to the left of   12
2     0   to the left of   16
3     1   to the left of    2
4     2  to the right of    1
5     3               on    9
6     3  to the right of   14
7     5   to the left of   14
8     6               of   12
9     6   to the left of   16
10    7   to the left of   10
11    7               of   14
12    8  to the right of   13
13    9    surrounded by   16
14    9      surrounding   14
15   10  to the right of    7
16   11               on    9
17   11  to the right of   14
18   12   to the left of   16
19   12  to the right of    0
20   13               of   14
21   13   to the left of    8
22   14   to the left of    3
23   14   to the left of   11
24   14               in    9
25   14    surrounded by    9
26   14      in front of    0
27   14  to the right of    5
28   14               on    9
29   15               on    9
30   16  to the right of   12
31   16  to the right of    0
32   16               in    4
33   16  to the right of    6