Is there a train in the shelter?
Yes, there is a train in the shelter.
   src        edge_attr  dst
0    4   to the left of    6
1    5   to the left of    6
2    6  to the right of    4
3    6  to the right of    5
4    6  to the right of    7
5    7   to the left of    6
6    7               at    0
7    7               in    0