Which color does the fence that is made of metal have?
The fence has black color.
    src        edge_attr  dst
0     0  to the right of   10
1     0   to the left of    4
2     0               of   14
3     0  to the right of    3
4     0   to the left of    9
5     1   to the left of    4
6     1  to the right of   10
7     2   to the left of   14
8     2   to the left of   10
9     3   to the left of    0
10    4  to the right of   10
11    4  to the right of    1
12    4  to the right of    0
13    5   to the left of   13
14    8               on   14
15    8               on   11
16    8  to the right of   10
17    9  to the right of    0
18   10  to the right of    2
19   10   to the left of    1
20   10   to the left of    0
21   10  to the right of   12
22   10   to the left of    4
23   10   to the left of    8
24   12   to the left of   10
25   12   to the left of   14
26   13  to the right of    5
27   14  to the right of   12
28   14  to the right of    2