What is the bird standing on?
The bird is standing on the branch.
    src        edge_attr  dst
0     1      standing on   13
1     1  to the right of    4
2     2  to the right of    4
3     3  to the right of    4
4     3   to the left of   11
5     4   to the left of    1
6     4   to the left of   10
7     4   to the left of    3
8     4   to the left of   11
9     4   to the left of    2
10    6  to the right of   15
11    6  to the right of   16
12    7  to the right of   15
13    7  to the right of   16
14   10  to the right of    4
15   11  to the right of    3
16   11  to the right of    4
17   15   to the left of    7
18   15   to the left of    6
19   16   to the left of    6
20   16   to the left of    7