What is the color of the sky?
The sky is gray.
   src        edge_attr  dst
0    0  to the right of    6
1    0   to the left of   12
2    1   to the left of    7
3    6   to the left of   12
4    6   to the left of    0
5    7  to the right of    1
6   12  to the right of    0
7   12  to the right of    6