vim:fdm=marker
 vim:foldtext=getline(v\:foldstart).'\ \ \ /'.v\:foldlevel.'...'.(v\:foldend-v\:foldstart)
 foldtext=getline(v\:foldstart).'...'.(v\:foldend-v\:foldstart)

Vim folding seems to be limited to 20 levels.

--- 1 ---{{{1
1

--- 2 ---{{{2
2

--- 3 ---{{{3
3

--- 4 ---{{{4
4

--- 5 ---{{{5
5

--- 6 ---{{{6
6

--- 7 ---{{{7
7

--- 8 ---{{{8
8

--- 9 ---{{{9
9

--- 10 ---{{{10
10

--- 11 ---{{{11
11

--- 12 ---{{{12
12

--- 13 ---{{{13
13

--- 14 ---{{{14
14

--- 15 ---{{{15
15

--- 16 ---{{{16
16

--- 17 ---{{{17
17

--- 18 ---{{{18
18

--- 19 ---{{{19
19

--- 20 ---{{{20
20

--- 21 ---{{{21
21

--- 22 ---{{{22
22

--- 23 ---{{{23
23

--- 24 ---{{{24
24

--- 25 ---{{{25
25

--- 26 ---{{{26
26

--- 27 ---{{{27
27

--- 28 ---{{{28
28

--- 29 ---{{{29
29

--- 30 ---{{{30
30

--- 31 ---{{{31
31

--- 32 ---{{{32
32

--- 33 ---{{{33
33

--- 34 ---{{{34
34

--- 35 ---{{{35
35

--- 36 ---{{{36
36

--- 37 ---{{{37
37

--- 38 ---{{{38
38

--- 39 ---{{{39
39

--- 40 ---{{{40
40

~~~ ~~~ THE END ~~~ ~~~{{{1