Are there either any black cows or zebras?
Yes, there is a black cow.
     src        edge_attr  dst
0      2   to the left of   25
1      2   to the left of   10
2      2   to the left of   20
3      2  to the right of   26
4      2   to the left of    5
..   ...              ...  ...
150   26   to the left of   14
151   26   to the left of   13
152   26   to the left of   23
153   26   to the left of   25
154   26   to the left of    8

[155 rows x 3 columns]