Is this a bus or a train?
This is a train.
    src        edge_attr  dst
0     0   to the left of    6
1     1   to the left of    2
2     1   to the left of    6
3     1   to the left of    3
4     2        on top of    6
5     2  to the right of    1
6     2   to the left of    3
7     3  to the right of    2
8     3  to the right of    1
9     3  to the right of    6
10    3           beside    1
11    3  to the right of    5
12    4   on the side of    1
13    5   to the left of    3
14    6  to the right of    1
15    6  to the right of    0
16    6   to the left of    3