Does the tunnel have white color?
Yes, the tunnel is white.
    src        edge_attr  dst
0     1  to the right of    4
1     2   to the left of    5
2     2   to the left of    6
3     4   to the left of    1
4     5               by    4
5     5  to the right of    2
6     5   to the left of    9
7     6   to the left of    9
8     6  to the right of    2
9     8               by    4
10    8               by    3
11    9  to the right of    5
12    9  to the right of    6