Is there a bus in the picture?
No, there are no buses.
    src        edge_attr  dst
0     0          holding    1
1     3               by    4
2     7   to the left of   11
3     7               by    2
4     7  to the right of    8
5     7               in    3
6     7               by    4
7     8   to the left of    7
8     9          holding    1
9     9          holding    5
10   11  to the right of    7