What color is the mask?
The mask is red.
    src        edge_attr  dst
0     0   to the left of   13
1     0  to the right of   11
2     0  to the right of    8
3     0  to the right of    6
4     1   to the left of    4
..  ...              ...  ...
60   19   to the left of   16
61   19   to the left of   11
62   19   to the left of    6
63   20   to the left of   11
64   20   to the left of   16

[65 rows x 3 columns]