What type of furniture is made of wood?
The furniture is a shelf.
    src        edge_attr  dst
0     2   to the left of    5
1     2   to the left of    3
2     2   to the left of    6
3     3  to the right of    7
4     3  to the right of    4
5     3  to the right of    2
6     4   to the left of    5
7     4   to the left of    3
8     4   to the left of    6
9     5  to the right of    4
10    5  to the right of    2
11    6  to the right of    2
12    6  to the right of    7
13    6  to the right of    4
14    7   to the left of    6
15    7   to the left of    3