What are the books on?
The books are on the shelves.
     src        edge_attr  dst
0      0  to the right of   23
1      0   to the left of   21
2      0  to the right of   11
3      0   to the left of   16
4      0       sitting on   12
..   ...              ...  ...
119   25   to the left of   17
120   26  to the right of   18
121   26   to the left of   25
122   26   to the left of   14
123   26   to the left of   17

[124 rows x 3 columns]