What item of furniture isn't empty?
The piece of furniture is a desk.
    src        edge_attr  dst
0     0  to the right of    4
1     0  to the right of    3
2     0   to the left of    5
3     2               on    1
4     2  to the right of    5
5     3   to the left of    0
6     4   to the left of    0
7     5   to the left of    2
8     5  to the right of    0
9     7               on    6
10    8               on    1