Do you see helmets in the picture?
No, there are no helmets.
    src        edge_attr  dst
0     0   to the left of    9
1     0               on    4
2     0  to the right of   11
3     1   to the left of    7
4     2  to the right of    3
5     2   to the left of    7
6     3   to the left of    7
7     3               on    4
8     3   to the left of    2
9     4  to the right of   11
10    4   to the left of    7
11    5  to the right of    6
12    6   to the left of    5
13    6   to the left of    7
14    6   to the left of   16
15    7  to the right of    9
16    7  to the right of    6
17    7  to the right of    1
18    7  to the right of    2
19    7  to the right of    3
20    7  to the right of    4
21    9  to the right of    0
22    9   to the left of    7
23   11   to the left of    4
24   11   to the left of    0
25   11   to the left of   15
26   14               of   15
27   15  to the right of   11
28   16  to the right of    6