What's covered by the snow?
The trees are covered by the snow.
    src        edge_attr  dst
0     0   to the left of    2
1     0  to the right of    8
2     0   to the left of    7
3     1   to the left of    7
4     2  to the right of    0
5     2  to the right of    8
6     2   to the left of    7
7     5       covered by    7
8     6               in    7
9     6   to the left of    7
10    7         covering    5
11    7  to the right of    1
12    7  to the right of    0
13    7  to the right of    6
14    7  to the right of    2
15    7  to the right of    8
16    7               on    5
17    8               in    7
18    8   to the left of    0
19    8   to the left of    7
20    8   to the left of    2