Is the smoke red or black?
The smoke is black.
    src        edge_attr  dst
0     2               on    1
1     2  to the right of    3
2     3   to the left of    2
3     3  to the right of    7
4     3  to the right of    4
5     4  to the right of    6
6     4   to the left of    3
7     5  to the right of    6
8     6   to the left of    4
9     6   to the left of    7
10    6   to the left of    5
11    7  to the right of    6
12    7   to the left of    3
13    9  to the right of   10
14   10   to the left of    9
15   10  to the right of   12
16   10  to the right of   11
17   11  to the right of   12
18   11   to the left of   10
19   12   to the left of   11
20   12   to the left of   10