What is the sand covering?
The sand is covering the sea shore.
    src        edge_attr  dst
0     0               on    5
1     0   to the left of   10
2     3  to the right of    6
3     3       covered by    4
4     4   to the left of   10
5     4         covering    3
6     6        parked at    5
7     6               in    1
8     6   to the left of    3
9     6   to the left of   10
10   10  to the right of    6
11   10  to the right of    4
12   10               on    5
13   10  to the right of    0
14   11               on    5
15   11   to the left of   13
16   13               of   12
17   13  to the right of   11