Are there either tractors or ambulances?
No, there are no ambulances or tractors.
    src        edge_attr  dst
0     0  to the right of    8
1     0  to the right of    2
2     0  to the right of    6
3     1   to the left of   14
4     1  to the right of   17
5     2   to the left of    0
6     2   to the left of   20
7     3   to the left of    5
8     3  to the right of   13
9     4   to the left of    5
10    4   to the left of   12
11    4  to the right of   19
12    4  to the right of   13
13    4             near    5
14    5  to the right of    4
15    5  to the right of   13
16    5  to the right of    3
17    5  to the right of   15
18    5             near    4
19    6   to the left of    0
20    6   to the left of   20
21    7   to the left of   14
22    8   to the left of   20
23    8   to the left of    0
24   10   to the left of   16
25   11  to the right of   16
26   12  to the right of   13
27   12  to the right of    4
28   13   to the left of    4
29   13   to the left of    5
30   13   to the left of    3
31   13   to the left of   12
32   14  to the right of   17
33   14  to the right of    1
34   14  to the right of    7
35   15   to the left of    5
36   16  to the right of   10
37   16   to the left of   11
38   17   to the left of   14
39   17   to the left of    1
40   19   to the left of    4
41   20  to the right of    8
42   20  to the right of    2
43   20  to the right of    6