What's on the cart?
The tray is on the cart.
    src        edge_attr  dst
0     0   to the left of   18
1     0   to the left of   12
2     0   to the left of    9
3     0   to the left of   16
4     0   to the left of   13
..  ...              ...  ...
93   23  to the right of   14
94   23  to the right of   15
95   24   to the left of   12
96   24   to the left of   16
97   25   to the left of   13

[98 rows x 3 columns]