Are the papers on a shelf?
No, the papers are on a desk.
    src        edge_attr  dst
0     0  to the right of   15
1     1               on    0
2     1               on    9
3     1  to the right of   14
4     1  to the right of    5
5     2               on    5
6     2               on    0
7     2  to the right of    3
8     3   to the left of    7
9     3   to the left of    2
10    3  to the right of   19
11    3   to the left of   18
12    4  to the right of   19
13    4   to the left of    7
14    5   to the left of    7
15    5   to the left of    1
16    6  to the right of   16
17    6  to the right of    8
18    7  to the right of    4
19    7  to the right of   14
20    7  to the right of    3
21    7  to the right of    5
22    8   to the left of    6
23    9  to the right of   19
24   10               in   13
25   10               by    5
26   11  to the right of   17
27   14   to the left of    1
28   14   to the left of    7
29   15   to the left of    0
30   16   to the left of    6
31   16               on   12
32   17   to the left of   11
33   18  to the right of    3
34   18               on   14
35   19   to the left of    9
36   19   to the left of    3
37   19               of   13
38   19   to the left of    4