What is on the sign?
The letter is on the sign.
    src        edge_attr  dst
0     0  to the right of   10
1     1               on   11
2     2   to the left of    4
3     2             near   10
4     2   to the left of    9
5     2  to the right of   10
6     3  to the right of   10
7     4  to the right of   12
8     4  to the right of    2
9     6  to the right of   10
10    7   to the left of   12
11    9  to the right of    2
12   10   to the left of    2
13   10   to the left of    0
14   10   to the left of    6
15   10   to the left of    3
16   10             near    2
17   12   to the left of    4
18   12  to the right of    7