What vegetable is on the shelf?
The vegetable is lettuce.
    src        edge_attr  dst
0     0  to the right of   14
1     0  to the right of    7
2     1  to the right of    6
3     1  to the right of   15
4     1  to the right of   14
5     1  to the right of    2
6     1  to the right of    8
7     1               on   11
8     2   to the left of    1
9     2  to the right of    5
10    3   to the left of   10
11    4  to the right of    7
12    4  to the right of   14
13    4  to the right of   12
14    5   to the left of    6
15    5   to the left of    2
16    6   to the left of    1
17    6  to the right of    5
18    7   to the left of    0
19    7   to the left of   12
20    7  to the right of    9
21    7   to the left of    4
22    8               on   11
23    8  to the right of   15
24    8   to the left of    1
25    9   to the left of    7
26   10  to the right of    3
27   12  to the right of    7
28   12   to the left of    4
29   13   to the left of   15
30   13   to the left of   14
31   14  to the right of   15
32   14   to the left of    0
33   14  to the right of   13
34   14   to the left of    1
35   14   to the left of    4
36   14               on   11
37   15   to the left of    1
38   15   to the left of    8
39   15   to the left of   14
40   15  to the right of   13