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