let jsNull =Js.Nullable.null
let jsUndefined =Js.Nullable.undefined
let result1: Js.Nullable.t<string> =Js.Nullable.return("hello")
let result2: Js.Nullable.t<int> =Js.Nullable.fromOption(Some(10))
let result3: option<int> =Js.Nullable.toOption(Js.Nullable.return(10))