What is the fence in front of?
The fence is in front of the trees.
    src        edge_attr  dst
0     2   to the left of    4
1     2   to the left of   12
2     3   to the left of    7
3     4   to the left of   11
4     4  to the right of    2
5     5  to the right of    7
6     5  to the right of   12
7     5  to the right of    6
8     6  to the right of    7
9     6   to the left of    5
10    7   to the left of    6
11    7   to the left of    5
12    7  to the right of    3
13    7  to the right of    9
14    8           behind   14
15    9   to the left of    7
16   11  to the right of    4
17   12  to the right of    2
18   12   to the left of    5
19   14      in front of    8