Do you see forks?
No, there are no forks.
    src        edge_attr  dst
0     0   to the left of    8
1     0   to the left of    1
2     0               on    3
3     1   to the left of    8
4     1  to the right of    0
5     2   to the left of    7
6     3               on    4
7     3             with   10
8     3             with    6
9     4               on    2
10    5               on    4
11    5   to the left of    9
12    6               on    3
13    7  to the right of    2
14    8  to the right of    0
15    8  to the right of    1
16    8               on    4
17    9               on    4
18    9  to the right of    5
19   10               on    3