Delegating handler to capture request processing times

gistfile1.fs

    type TimingHandler() =
        inherit DelegatingHandler ()

        let cont (sw : Stopwatch) (t: Task<HttpResponseMessage>) =
            sw.Stop()
            debug "request time: %i" sw.ElapsedMilliseconds
            t.Result // dont like this
                     
        override this.SendAsync (request, token) =
            let sw = new Stopwatch()
            sw.Start()
            base.SendAsync(request, token)
                .ContinueWith(cont sw, token)