Which color is this truck?
The truck is gray.
    src        edge_attr  dst
0     0  to the right of   15
1     0  to the right of    6
2     0   to the left of   10
3     0             near   15
4     1   to the left of    9
5     2   to the left of   12
6     2  to the right of    4
7     3  to the right of   15
8     4   to the left of   10
9     4  to the right of   15
10    4   to the left of    2
11    5   to the left of   10
12    5  to the right of    6
13    5  to the right of    8
14    5  to the right of   15
15    6   to the left of    0
16    6   to the left of    5
17    6  to the right of   15
18    7   to the left of    9
19    7   to the left of   10
20    8  to the right of   15
21    8   to the left of    5
22    9   to the left of   10
23    9  to the right of    7
24    9  to the right of    1
25   10  to the right of    7
26   10  to the right of    4
27   10  to the right of    0
28   10  to the right of    9
29   10  to the right of    5
30   11  to the right of   15
31   12  to the right of    2
32   15   to the left of    3
33   15   to the left of    4
34   15   to the left of   11
35   15   to the left of    0
36   15   to the left of    5
37   15   to the left of    6
38   15   to the left of    8
39   15             near    0