What is the truck carrying?
The truck is carrying logs.
    src        edge_attr  dst
0     1   to the left of   12
1     1   to the left of    9
2     2   to the left of   12
3     2   to the left of    9
4     4               by   13
5     6  to the right of   12
6     6  to the right of    9
7     9          pulling   14
8     9         carrying   12
9     9   to the left of    6
10    9   to the left of   14
11    9   to the left of   11
12    9          full of   12
13    9  to the right of    2
14    9  to the right of    1
15   11  to the right of    9
16   12   to the left of    6
17   12   to the left of   14
18   12  to the right of    2
19   12  to the right of    1
20   14        pulled by    9
21   14   on the back of    9
22   14  to the right of    9
23   14  to the right of   12