What is covered with leaves?
The trees are covered with leaves.
    src        edge_attr  dst
0     0  to the right of    1
1     0  to the right of   10
2     0      standing in    7
3     0  to the right of   11
4     1               of   10
5     1   to the left of    4
6     1   to the left of    2
7     1   to the left of   11
8     1  to the right of    8
9     1   to the left of    0
10    2  to the right of   10
11    2  to the right of    1
12    4  to the right of   10
13    4  to the right of    1
14    4  to the right of   11
15    8   to the left of    1
16    8   to the left of   11
17    8   to the left of   10
18   10  to the right of    8
19   10   to the left of    4
20   10   to the left of    2
21   10   to the left of    0
22   11   to the left of    0
23   11  to the right of    1
24   11   to the left of    4
25   11  to the right of    8
26   12     covered with    6