Is the ground gray or yellow?
The ground is gray.
    src        edge_attr  dst
0     0  to the right of   10
1     0  to the right of   12
2     0  to the right of   14
3     1  to the right of    5
4     1   to the left of   13
5     1  to the right of    8
6     2   to the left of    3
7     3  to the right of    2
8     3   to the left of    9
9     4  to the right of   11
10    4   to the left of   13
11    5   to the left of    1
12    5   to the left of    8
13    8   to the left of    1
14    8  to the right of    5
15    8   to the left of   12
16    8   to the left of   14
17    9  to the right of   14
18    9  to the right of    3
19   10   to the left of    0
20   11   to the left of    4
21   12  to the right of    8
22   12   to the left of    0
23   13  to the right of    1
24   13  to the right of    4
25   14  to the right of    8
26   14   to the left of    9
27   14   to the left of    0