Which kind of vehicle is the boy in front of?
The boy is in front of the car.
    src        edge_attr  dst
0     0             near    4
1     0           behind    4
2     0   to the left of    4
3     0  to the right of    2
4     0   to the left of    6
5     0   to the left of    5
6     1  to the right of    2
7     2   to the left of    0
8     2   to the left of    1
9     4             with    1
10    4      in front of    0
11    4          holding    1
12    4  to the right of    0
13    4          wearing    5
14    4             near    0
15    4  to the right of    7
16    5  to the right of    7
17    5  to the right of    0
18    6  to the right of    0
19    7   to the left of    5
20    7   to the left of    4