What is the green bush covered by?
The bush is covered by the snow.
    src        edge_attr  dst
0     1  to the right of    2
1     1  to the right of    6
2     2   to the left of    8
3     2   to the left of    1
4     2  to the right of    6
5     4   to the left of    8
6     6   to the left of    2
7     6   to the left of    8
8     6   to the left of    1
9     8  to the right of    2
10    8  to the right of    4
11    8  to the right of    6
12   10   on the side of    9
13   10       covered by   12
14   12         covering   10
15   12        on top of    9