What is on the dock?
The truck is on the dock.
    src        edge_attr  dst
0     0  to the right of    6
1     1   to the left of    3
2     1   to the left of    2
3     1   to the left of    9
4     1  to the right of    4
5     2        parked on    0
6     2  to the right of    9
7     2               on    0
8     2  to the right of    1
9     3  to the right of    1
10    3  to the right of    9
11    4   to the left of    1
12    4   to the left of    9
13    6   to the left of    0
14    9   to the left of    2
15    9   to the left of    3
16    9  to the right of    1
17    9  to the right of    4