What color are the trees?
The trees are dark.
    src        edge_attr  dst
0     0   to the left of    6
1     0  to the right of    3
2     1  to the right of    3
3     1   to the left of    6
4     2               on    5
5     2  to the right of    7
6     2   to the left of    6
7     2  to the right of    3
8     3               on    5
9     3   to the left of    0
10    3   to the left of    4
11    3   to the left of    1
12    3   to the left of    2
13    4  to the right of    3
14    4   to the left of    6
15    6  to the right of    4
16    6  to the right of    0
17    6  to the right of    2
18    6  to the right of    1
19    7   to the left of    2