What is common to the graffiti and the dirt?
The color, both the graffiti and the dirt are black.
   src        edge_attr  dst
0    0  to the right of    1
1    1   to the left of    0
2    1   to the left of    4
3    2               on    1
4    4  to the right of    5
5    4  to the right of    1
6    5   to the left of    4