Which color is the box in the center?
The box is yellow.
    src        edge_attr  dst
0     1               on    0
1     1  to the right of    9
2     2   to the left of   13
3     4               by    5
4     4  to the right of    5
5     5   to the left of    4
6     6  to the right of   11
7     9   to the left of    1
8    11   to the left of   12
9    11   to the left of    6
10   12  to the right of   11
11   13  to the right of    2