Are there either any glasses or fences in the image?
Yes, there is a fence.
    src        edge_attr  dst
0     1  to the right of    4
1     1  to the right of    9
2     4   to the left of    1
3     4               in    8
4     5  to the right of   12
5     6   to the left of    7
6     6   to the left of   10
7     7               of   15
8     7  to the right of    6
9     9   to the left of    1
10   10               of   15
11   10  to the right of    6
12   12   to the left of   13
13   12   to the left of    5
14   12   to the left of   15
15   13  to the right of   12
16   15               in    3
17   15  to the right of   12