The bus is in front of what?
The bus is in front of the tree.
    src        edge_attr  dst
0     0   to the left of    6
1     0   to the left of   12
2     0  to the right of   17
3     0  to the right of   16
4     1               of   12
..  ...              ...  ...
89   21   to the left of    9
90   21   to the left of    1
91   21      in front of   20
92   21   to the left of   12
93   21   to the left of    5

[94 rows x 3 columns]