Which material is the fence made of, iron or plastic?
The fence is made of iron.
    src        edge_attr  dst
0     0               of    8
1     0   to the left of   12
2     0   to the left of   11
3     0   to the left of    3
4     0   to the left of    2
5     0   to the left of    7
6     0   to the left of    6
7     1  to the right of   13
8     1  to the right of    8
9     2               of    8
10    2  to the right of    3
11    2  to the right of    0
12    2  to the right of   11
13    2  to the right of    7
14    2   to the left of   13
15    2  to the right of   12
16    3   to the left of   13
17    3   to the left of    2
18    3               of    7
19    3  to the right of    0
20    5  to the right of   13
21    5  to the right of    8
22    6  to the right of    0
23    6   to the left of   13
24    6               of    7
25    7  to the right of    0
26    7   to the left of    2
27    7   to the left of   13
28    8   to the left of    1
29    8   to the left of    5
30    8   to the left of   13
31    8            below    9
32    9   to the left of   13
33   11  to the right of    0
34   11               of    7
35   11   to the left of   12
36   11   to the left of    2
37   12               of    7
38   12  to the right of   11
39   12   to the left of    2
40   12  to the right of    0
41   12   to the left of   13
42   13   to the left of    1
43   13  to the right of    2
44   13  to the right of    7
45   13  to the right of    3
46   13  to the right of    6
47   13  to the right of    8
48   13  to the right of    9
49   13   to the left of    5
50   13  to the right of   12