Of which color is the ground?
The ground is black.
   src        edge_attr  dst
0    0               of    7
1    0  to the right of    1
2    0  to the right of    4
3    1   to the left of    0
4    2   to the left of    8
5    2               of    7
6    4   to the left of    0
7    4           riding    7
8    8               of    7
9    8  to the right of    2