USE OCaml language not in any other language

Modify the following code to eliminate the words repeated by itself more than 3 times.

let rec destutter list =

match list with

| [] -> []

| [hd] -> [hd] | hd1 :: hd2 :: tl ->

if hd1 = hd2 then destutter (hd2 :: tl)

else hd1 :: destutter (hd2 :: tl)

;;

#destutter ["hey";"hey";"hey";"man!"];;

Tthe output is

n!"];; - : string list = ["hey"; "man!"]

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similarly modify the code if i give

#destutter ["hey";"hey";"hey";"man!"];;

the result will be

- : string list = ["hey"; "hey"; "man!"]