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