What is the shape of the white container?
The container is square.
    src        edge_attr  dst
0     0             with   13
1     0               on    4
2     1  to the right of   11
3     1   to the left of    4
4     2   to the left of   12
5     3  to the right of   11
6     4  to the right of    1
7     5   to the left of    9
8     6   to the left of    7
9     7  to the right of   16
10    7  to the right of    9
11    7  to the right of    6
12    8               of    7
13    8  to the right of    9
14    8  to the right of   16
15    9  to the right of    5
16    9   to the left of    7
17    9   to the left of    8
18   10   to the left of   14
19   11   to the left of    3
20   11   to the left of    1
21   12  to the right of    2
22   14  to the right of   10
23   16               on    7
24   16   to the left of    8
25   16   to the left of    7