What are the vehicles to the left of the vehicle the tree is in front of?
The vehicles are cars.
    src        edge_attr  dst
0     1   to the left of    6
1     2  to the right of   18
2     2  to the right of    4
3     3  to the right of   18
4     3  to the right of   12
..  ...              ...  ...
59   20   to the left of    8
60   20   to the left of    3
61   21  to the right of   22
62   22   to the left of   21
63   22   to the left of    9

[64 rows x 3 columns]