What is the color of the bus in the middle?
The bus is yellow.
    src        edge_attr  dst
0     0   to the left of    6
1     0  to the right of   10
2     0             near    6
3     0  to the right of   13
4     1  to the right of    5
5     1  to the right of   12
6     1  to the right of    8
7     2  to the right of   13
8     2  to the right of   10
9     4   to the left of   13
10    4   to the left of   12
11    5   to the left of    1
12    5   to the left of   13
13    5   to the left of   12
14    5   to the left of    9
15    6  to the right of    0
16    6          next to    0
17    6  to the right of   10
18    8   to the left of    9
19    8   to the left of   13
20    8   to the left of    1
21    9  to the right of    5
22    9  to the right of    8
23   10   to the left of   15
24   10   to the left of    0
25   10  to the right of   13
26   10   to the left of    6
27   10   to the left of    2
28   10  to the right of   12
29   12  to the right of    5
30   12  to the right of    4
31   12   to the left of   10
32   12   to the left of    1
33   13  to the right of    8
34   13   to the left of    2
35   13   to the left of   10
36   13  to the right of    4
37   13   to the left of    0
38   13  to the right of    5
39   14  to the right of   15
40   15   to the left of   14
41   15  to the right of   10