Are there both a fence and a zebra?
Yes, there are both a zebra and a fence.
    src        edge_attr  dst
0     2   to the left of    3
1     2   to the left of    8
2     2               of    8
3     3  to the right of   15
4     3  to the right of    2
5     3   to the left of   13
6     5               of    8
7     6               of    8
8     6   to the left of    8
9     7               of    8
10    7   to the left of    8
11    7   to the left of    9
12    7   to the left of   12
13    8  to the right of    6
14    8  to the right of    2
15    8  to the right of    7
16    9  to the right of    7
17   11               of    8
18   12  to the right of    7
19   13  to the right of    3
20   13               of    8
21   14               of    8
22   15   to the left of    3