type FizzBuzz = { n: int; s: string } with
    member x.gizz = x.update(7, "Gizz")
    member x.buzz = x.update(5, "Buzz")
    member x.update(m, s) = { x with s = x.s + if x.n % m = 0 then s else "" }
    override x.ToString() =
        if x.s = "" then string x.n else x.s
 
let wrap n = { n = n; s = "" }
 
type System.Int32 with
    member x.fizz = wrap(x).update(3, "Fizz")
    member x.buzz = wrap(x).update(5, "Buzz")
 
let p = printfn "%O"
 
p 1 .fizz.buzz // 1
p 3 .fizz.buzz // Fizz
p 5 .fizz.buzz // Buzz
p 15 .fizz.buzz // FizzBuzz
p 997 .fizz.buzz // 997
p 7 .fizz.buzz.gizz // Gizz
p 21 .fizz.buzz.gizz // FizzGizz
p 35 .fizz.buzz.gizz // BuzzGizz
p 105 .fizz.buzz.gizz // FizzBuzzGizz
p 105 .fizz.gizz.buzz // FizzGizzBuzz
 

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