What vehicle is in front of the tall mountains?
The vehicle is a train.
    src        edge_attr  dst
0     2           behind    3
1     3             near   10
2     3               on    8
3     3  to the right of   10
4     3      in front of    2
5     3      coming down    8
6     4               in   11
7     4   to the left of   12
8     4   to the left of   13
9     5               on    2
10    9  to the right of   10
11   10             near    3
12   10   to the left of    9
13   10   to the left of    3
14   10   to the left of   13
15   11   to the left of   13
16   12  to the right of    4
17   13  to the right of    4
18   13  to the right of   11
19   13  to the right of   10