On which side is the cow?
The cow is on the left of the image.
   src        edge_attr  dst
0    0  to the right of    3
1    1  to the right of    3
2    2               on    0
3    2  to the right of    3
4    3   to the left of    0
5    3   to the left of    2
6    3   to the left of    1