How clean is the sheep on the left?
The sheep is dirty.
    src   edge_attr  dst
0     1   on top of    8
1     1          by    9
2     2   on top of    8
3     2          by    9
4     4   on top of    8
5     4          by    9
6     5   on top of    8
7     5      eating    4
8     5   on top of    4
9     5  grazing on    4
10    5  grazing on    8
11    6   on top of    4
12    6  grazing on    8
13    6   on top of    8
14    6      eating    4
15    6  grazing on    4
16    7      eating    4
17    7   on top of    4
18    7  grazing on    8
19    7   on top of    8
20    7  grazing on    4
21    9   on top of    8
22    9   on top of    4