On which side is the fork?
The fork is on the left of the image.
    src        edge_attr  dst
0     1   to the left of   18
1     3   to the left of   11
2     5  to the right of   18
3     5   to the left of   11
4     7   to the left of   10
5     8   to the left of   10
6    10  to the right of    7
7    10  to the right of    8
8    11  to the right of    5
9    11  to the right of    3
10   13   to the left of   14
11   14  to the right of   13
12   18   to the left of    5
13   18  to the right of    1