Which side is the fork on?
The fork is on the left of the image.
    src        edge_attr  dst
0     0               on    2
1     0   to the left of   11
2     0   to the left of    6
3     0   to the left of    1
4     1  to the right of    9
5     1  to the right of   10
6     1  to the right of    0
7     2       stacked on    3
8     2   to the left of    6
9     3   to the left of   12
10    4  to the right of   10
11    4   to the left of    6
12    5   to the left of   12
13    5   to the left of   13
14    6  to the right of    2
15    6  to the right of    4
16    6  to the right of    9
17    6  to the right of   10
18    6  to the right of    0
19    9   to the left of    6
20    9   to the left of    1
21   10   to the left of    6
22   10   to the left of    1
23   10   to the left of    4
24   11  to the right of    0
25   12  to the right of    5
26   12  to the right of    3
27   13  to the right of    5