What are the books sitting on?
The books are sitting on the desk.
    src        edge_attr  dst
0     0   to the left of    3
1     1       hanging on    0
2     1   to the left of    3
3     2       sitting on    8
4     2   to the left of    3
5     2  to the right of    5
6     3  to the right of    1
7     3  to the right of    2
8     3  to the right of    5
9     3  to the right of    0
10    4          next to    8
11    4           behind    8
12    4   to the left of    7
13    4             near    8
14    5       sitting on    8
15    5  to the right of    7
16    5   to the left of    2
17    5   to the left of    3
18    6  to the right of    8
19    7       sitting on    8
20    7  to the right of    4
21    7   to the left of    5
22    8      in front of    4
23    8             near    4
24    8   to the left of    6