Is there a truck or a train that is not red?
No, there is a train but it is red.
   src        edge_attr  dst
0    0  to the right of    3
1    2  to the right of    3
2    3   to the left of    0
3    3   to the left of    2
4    3   to the left of    7
5    3   to the left of    5
6    5  to the right of    3
7    7  to the right of    3