What is the color of the arrow?
The arrow is black.
    src        edge_attr  dst
0     0               on    8
1     1   to the left of    9
2     2  to the right of    3
3     2   to the left of    8
4     3   to the left of    9
5     3   to the left of    2
6     3  to the right of    4
7     4   to the left of    9
8     4   to the left of    3
9     5   to the left of    9
10    6   to the left of    8
11    7               on    3
12    7   to the left of    8
13    8  to the right of    9
14    8  to the right of    7
15    8  to the right of    6
16    8  to the right of    2
17    9  to the right of    1
18    9   to the left of   10
19    9  to the right of    4
20    9  to the right of    3
21    9   to the left of    8
22    9  to the right of    5
23   10  to the right of    9