What is the color of the tail?
The tail is orange.
   src        edge_attr  dst
0    1   to the left of    3
1    1   to the left of    6
2    1  to the right of    4
3    3  to the right of    1
4    3  to the right of    4
5    4   to the left of    6
6    4   to the left of    1
7    4   to the left of    3
8    6  to the right of    1
9    6  to the right of    4