What is used to make the balcony that looks black?
The balcony is made of metal.
    src        edge_attr  dst
0     0   to the left of    8
1     0     hanging over    4
2     1  to the right of    6
3     1  to the right of    3
4     2  to the right of    5
5     2  to the right of    3
6     2  to the right of    6
7     3   to the left of    2
8     3   to the left of    1
9     3           behind    5
10    4               on    6
11    4             near    7
12    5   to the left of    2
13    6   to the left of    1
14    6   to the left of    2
15    7             near    4
16    8  to the right of    0