Which kind of animal is the tree behind of?
The tree is behind the horse.
    src        edge_attr  dst
0     1  to the right of    6
1     1  to the right of    3
2     2               of    4
3     3  to the right of    7
4     3   to the left of    4
5     3   to the left of    9
6     3   to the left of    1
7     3           behind    4
8     4            above    5
9     4  to the right of    3
10    4      in front of    6
11    4      in front of    3
12    5            below    4
13    5   to the left of    8
14    6   to the left of    9
15    6           behind    4
16    6   to the left of    1
17    7   to the left of    3
18    8               of    4
19    8  to the right of    5
20    9               of    4
21    9  to the right of    3
22    9  to the right of    6