What do you think is the mattress on?
The mattress is on the bed.
    src        edge_attr  dst
0     1  to the right of   12
1     1  to the right of   13
2     1  to the right of    3
3     2  to the right of    9
4     3   to the left of    1
5     3  to the right of   13
6     3   to the left of    5
7     3  to the right of   12
8     4  to the right of   16
9     5  to the right of   12
10    5  to the right of    3
11    5  to the right of   13
12    6               on    8
13    6   to the left of   13
14    6   to the left of   12
15    7               on    8
16    8               in    0
17    9   to the left of    2
18   10               on    8
19   11   to the left of   13
20   11   to the left of   12
21   12  to the right of    6
22   12   to the left of    5
23   12  to the right of   15
24   12   to the left of    1
25   12   to the left of    3
26   12  to the right of   11
27   13   to the left of    1
28   13  to the right of   15
29   13   to the left of    3
30   13   to the left of    5
31   13  to the right of   11
32   13  to the right of    6
33   15   to the left of   12
34   15   to the left of   13
35   16   to the left of    4