What do the people that to the left of the backpack wear?
The people wear a helmet.
    src        edge_attr  dst
0     2   to the left of    7
1     4  to the right of   14
2     4  to the right of    9
3     5  to the right of   15
4     7  to the right of    2
5     9   to the left of    4
6     9   to the left of   13
7    10   to the left of   11
8    10   to the left of   12
9    11               on   12
10   11  to the right of   10
11   11  to the right of   14
12   12  to the right of   14
13   12  to the right of   10
14   13  to the right of    9
15   13  to the right of   15
16   13             with    6
17   13          wearing    9
18   13             with    4
19   14          wearing   10
20   14   to the left of    4
21   14   to the left of   11
22   14   to the left of   12
23   15   to the left of    5
24   15   to the left of   13