What is the roof in front of?
The roof is in front of the trees.
    src        edge_attr  dst
0     0   to the left of    9
1     2      in front of   10
2     2   to the left of   15
3     3   to the left of    5
4     3  to the right of    8
5     3   to the left of   15
6     3  to the right of    7
7     4  to the right of    7
8     5  to the right of    8
9     5  to the right of    3
10    5   to the left of   16
11    6  to the right of    9
12    6   to the left of    7
13    7   to the left of    8
14    7  to the right of    9
15    7   to the left of    3
16    7  to the right of   20
17    7  to the right of    6
18    7   to the left of    4
19    8  to the right of    7
20    8  to the right of    9
21    8   to the left of    3
22    8   to the left of    5
23    8   to the left of   15
24    9   to the left of   12
25    9               in    1
26    9           behind   13
27    9               by   10
28    9   to the left of    6
29    9   to the left of   20
30    9   to the left of    7
31    9  to the right of    0
32    9   to the left of    8
33   10           behind   15
34   10      in front of   18
35   10           behind    2
36   12   to the left of   16
37   12   to the left of   15
38   12  to the right of    9
39   13      in front of    9
40   15      in front of   10
41   15  to the right of   12
42   15  to the right of    3
43   15  to the right of    2
44   15  to the right of    8
45   16               on    4
46   16  to the right of   12
47   16  to the right of    5
48   17           behind   18
49   18           behind   19
50   18           behind   10
51   19      in front of   18
52   20   to the left of    7
53   20  to the right of    9