Is the clear sky white or blue?
The sky is blue.
    src        edge_attr  dst
0     0               in    9
1     0   to the left of   10
2     1               in    9
3     2   to the left of   11
4     3               in    9
5     3   to the left of   10
6     4               on   13
7     5               in    9
8     6  to the right of   16
9     7   to the left of   11
10   10  to the right of    3
11   10  to the right of    0
12   10               in    9
13   11  to the right of    2
14   11  to the right of    7
15   14               in    9
16   15               in    9
17   16   to the left of    6
18   16               in   13