What's the hill covered with?
The hill is covered with snow.
    src        edge_attr  dst
0     1   to the left of    4
1     1   to the left of    7
2     2               on    3
3     3     covered with    2
4     4   to the left of    8
5     4  to the right of    1
6     4  to the right of    7
7     6               on    3
8     7  to the right of    1
9     7   to the left of    4
10    7   to the left of    8
11    8  to the right of    7
12    8  to the right of    4