What covers the blue mountains?
The clouds cover the mountains.
    src        edge_attr  dst
0     1             near    4
1     1      in front of    5
2     1  to the right of    3
3     2       covered by    9
4     2   to the left of   11
5     3   to the left of    1
6     3         lying on    6
7     3   to the left of    4
8     3   to the left of    8
9     4          next to    1
10    4  to the right of    3
11    5           behind    1
12    8  to the right of    3
13    9         covering    2
14   11  to the right of    2