$Immutable<T> of user defined values

[thecotne]

class Cotne {
  name: ?string

  setName(name) {
    this.name = name
  }
}

const cotne = new Cotne

cotne.name = "not cotne"// ok
cotne.setName("not cotne")// ok

const readonly_cotne: $Immutable<Cotne> = new Cotne

readonly_cotne.name = "not cotne"// should error
readonly_cotne.setName("not cotne")// should error

const readonly_cotne2: $Immutable<{ name: string }> = { name: 'cotne' }

readonly_cotne2.name = 'dsds'// should error

try