What color is the zebra behind the other zebra?
The zebra is white.
   src        edge_attr  dst
0    0  to the right of    1
1    0  to the right of    5
2    0  to the right of    9
3    0  to the right of    6
4    1   to the left of    0
5    4           behind    8
6    5   to the left of    0
7    6   to the left of    0
8    8      in front of    4
9    9   to the left of    0