The controller is on what?
The controller is on the picture.
    src        edge_attr  dst
0     0   to the left of   15
1     0   to the left of    2
2     1   to the left of   11
3     2  to the right of   15
4     2  to the right of    0
5     2   to the left of   11
6     2   to the left of    6
7     3  to the right of    8
8     3   to the left of   11
9     3   to the left of    6
10    4   to the left of    6
11    4   to the left of   11
12    6  to the right of    2
13    6  to the right of   14
14    6  to the right of    4
15    6  to the right of    3
16    7   to the left of    9
17    8   to the left of    3
18    8   to the left of   14
19    8   to the left of   11
20    9  to the right of    7
21   11  to the right of   15
22   11  to the right of    1
23   11  to the right of    2
24   11  to the right of    4
25   11  to the right of    8
26   11  to the right of   14
27   11  to the right of    3
28   12               on    9
29   12   to the left of   16
30   14   to the left of   11
31   14  to the right of    8
32   14   to the left of    6
33   15   to the left of    2
34   15  to the right of    0
35   15   to the left of   11
36   16  to the right of   12