What is on the wall?
The shelves are on the wall.
    src        edge_attr  dst
0     0      in front of    1
1     0   to the left of   15
2     1   to the left of    5
3     1   to the left of   19
4     1   to the left of    6
5     2  to the right of    8
6     2   to the left of   14
7     4   to the left of   12
8     4               on    9
9     4   to the left of   10
10    5      in front of   16
11    5   to the left of   18
12    5  to the right of    1
13    5   to the left of    7
14    5  to the right of   15
15    5      in front of   19
16    5   to the left of   16
17    6               in    5
18    6  to the right of    1
19    6   to the left of    7
20    7  to the right of    5
21    7  to the right of   10
22    7  to the right of   12
23    7  to the right of    6
24    7  to the right of   19
25    7  to the right of   18
26    8   to the left of    2
27    8      in front of    9
28    9           behind    8
29   10           behind   19
30   10   to the left of    7
31   10  to the right of    4
32   11   to the left of   12
33   11   to the left of   19
34   11               on    7
35   12   to the left of    7
36   12  to the right of   11
37   12  to the right of    4
38   13               on   14
39   14  to the right of    2
40   15   to the left of    5
41   15   to the left of   19
42   15               in    2
43   15  to the right of    0
44   16           behind    5
45   16  to the right of    5
46   16      in front of   19
47   18  to the right of    5
48   18   to the left of    7
49   18               of   12
50   19           behind   16
51   19      in front of   10
52   19  to the right of   11
53   19  to the right of    1
54   19  to the right of   15
55   19   to the left of    7
56   19           behind    5