Which material is that fence made of?
The fence is made of wood.
    src        edge_attr  dst
0     0  to the right of    3
1     1  to the right of   14
2     1   to the left of   13
3     3   to the left of   13
4     3   to the left of    0
5     4  to the right of   13
6     5  to the right of   10
7     5   to the left of    9
8     5   to the left of    8
9     6  to the right of    7
10    6          holding   13
11    7   to the left of    6
12    7   to the left of   13
13    7         covering   12
14    8  to the right of    5
15    9  to the right of    5
16   10               in    7
17   10   to the left of    5
18   11  to the right of   13
19   12       covered in    7
20   12       covered by    7
21   13  to the right of   14
22   13   to the left of    4
23   13   to the left of   11
24   13  to the right of    7
25   13  to the right of    3
26   13  to the right of    1
27   13             with    0
28   14   to the left of    1
29   14   to the left of   13