F# get attachment filename by httpclient

filename.fs

open System.Net.Http
open System.Net.Mime
open System.Text

///get fileName by ContentDisposition or random file name if null
let getFileName (msg: HttpResponseMessage) =
    let value = Option.ofObj msg.Content.Headers.ContentDisposition
    let result = 
        value
        |> Option.map (fun e -> e.FileName)
        |> Option.map (fun e -> Encoding.UTF8.GetString(Encoding.GetEncoding("ISO-8859-1").GetBytes(e)))
    match result with
    | Some(v) -> v
    | None -> System.IO.Path.GetRandomFileName()

let fileName = using(new HttpClient()) (fun e ->
    let msg = e.GetAsync("https://sukebei.nyaa.se/?page=download&tid=2154757").Result
    Utils.getFileName(msg)
)
printfn "%A" fileName