What color is the garbage can, black or red?
The garbage can is black.
    src        edge_attr  dst
0     0   to the left of   10
1     0   to the left of    9
2     1   to the left of    8
3     1   to the left of    9
4     1   to the left of   10
5     1   to the left of    3
6     2   to the left of    6
7     3  to the right of   12
8     3  to the right of    7
9     3  to the right of    1
10    5   to the left of   11
11    6  to the right of    2
12    7   to the left of    3
13    8  to the right of    1
14    9  to the right of    0
15    9  to the right of    1
16   10  to the right of    1
17   10  to the right of    0
18   11  to the right of    5
19   12   to the left of    3