Do you see any glasses or mirrors?
Yes, there is a mirror.
    src        edge_attr  dst
0     0  to the right of   21
1     0  to the right of   13
2     0  to the right of    6
3     0  to the right of    4
4     0  to the right of   10
..  ...              ...  ...
93   20  to the right of    8
94   21   to the left of    0
95   21  to the right of    9
96   21               on    8
97   21   to the left of   12

[98 rows x 3 columns]