What is the steam coming out of?
The steam is coming out of the train.
    src        edge_attr  dst
0     0   to the left of    6
1     0   to the left of    3
2     0   to the left of    9
3     0   to the left of    8
4     1  to the right of    5
5     2   to the left of    3
6     2  to the right of   11
7     2   to the left of    8
8     3  on the front of    8
9     3  to the right of    2
10    3  to the right of    0
11    4  to the right of    5
12    4  to the right of   13
13    5   to the left of    1
14    5   to the left of    4
15    6        on top of    8
16    6  to the right of    0
17    7               of    8
18    7    coming out of    8
19    8  to the right of    2
20    8  to the right of   10
21    8  to the right of   12
22    8  to the right of    0
23    9  to the right of    0
24   10  to the right of   12
25   10   to the left of    8
26   11   to the left of    2
27   12   to the left of    8
28   12   to the left of   10
29   13   to the left of    4