Which color is the pen, blue or black?
The pen is blue.
    src        edge_attr  dst
0     0   to the left of    6
1     0   to the left of    7
2     1   to the left of    6
3     2   to the left of    6
4     3  to the right of    9
5     4   to the left of    9
6     6  to the right of    0
7     6  to the right of    1
8     6  to the right of    2
9     7  to the right of    0
10    9       sitting on   10
11    9  to the right of    4
12    9   to the left of    3