Which side is the pencil on?
The pencil is on the left of the image.
   src        edge_attr  dst
0    0  to the right of    4
1    1   to the left of    3
2    1   to the left of    5
3    2  to the right of    4
4    3  to the right of    1
5    4   to the left of    0
6    4   to the left of    2
7    5  to the right of    1