Which color is the dirt?
The dirt is gray.
    src        edge_attr  dst
0     0               of    9
1     0  to the right of    6
2     1  to the right of    5
3     2               of    9
4     2  to the right of   11
5     2  to the right of   12
6     5               in    8
7     5   to the left of    1
8     6               of    9
9     6   to the left of    0
10    7  to the right of   13
11    7               of    5
12    9               in    8
13    9               by    4
14   10               in    8
15   11  to the right of   12
16   11   to the left of    2
17   11               of    9
18   12               of    9
19   12   to the left of    2
20   12   to the left of   11
21   13   to the left of    7
22   13               of    5