On which side is the gray box?
The box is on the left of the image.
    src        edge_attr  dst
0     2   to the left of   10
1     2  to the right of    7
2     2   to the left of    8
3     2   to the left of    9
4     5   to the left of   11
5     5               on    8
6     7   to the left of   10
7     7   to the left of    2
8     7   to the left of    8
9     7   to the left of    9
10    8  to the right of    7
11    8  to the right of    2
12    9  to the right of    2
13    9  to the right of    7
14   10  to the right of    7
15   10  to the right of    2
16   11  to the right of    5