Which color is the pen?
The pen is green.
    src        edge_attr  dst
0     0  to the right of    8
1     2               in   12
2     4  to the right of    5
3     5               in   12
4     5   to the left of    4
5     5  to the right of    8
6     7               in   12
7     7       covered in    6
8     8   to the left of   11
9     8   to the left of    5
10    8   to the left of    0
11   10  to the right of   11
12   11  to the right of    8
13   11   to the left of   10