What is the glass in front of?
The glass is in front of the laptop.
   src        edge_attr  dst
0    0               on    3
1    0        on top of    3
2    0   to the left of    1
3    0      in front of    1
4    1           behind    0
5    1               on    3
6    1  to the right of    0
7    2   to the left of    4
8    4  to the right of    2