SecureRng = ref object of Rng
  hmacDrbgContext: ref HmacDrbgContext

proc new(T: typedesc[SecureRng]): T:type {....raises: [].}

method generate(rng: SecureRng; v: var openArray[byte]) {....raises: [], tags: [].}

method shuffle[T](rng: SecureRng; x: var openArray[T]) {....raises: [].}