What is the lock on?
The lock is on the suitcase.
    src        edge_attr  dst
0     0   to the left of    2
1     1  to the right of    5
2     1  to the right of    8
3     2       stacked on    1
4     2  to the right of    0
5     5   to the left of    1
6     7               on    3
7     7   to the left of    9
8     8   to the left of    1
9     9               on    3
10    9  to the right of    7
11   10               in    4