Are there flags in the scene?
Yes, there is a flag.
     src        edge_attr  dst
0      0  to the right of   26
1      0  to the right of   24
2      0   to the left of   15
3      0   to the left of   16
4      0   to the left of    3
..   ...              ...  ...
168   31  to the right of    5
169   31  to the right of   15
170   31  to the right of   27
171   31  to the right of   29
172   31  to the right of   25

[173 rows x 3 columns]