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