   INVALID_ARGUMENT indicates arguments that are problematic regardless of
   the state of the system (e.g., a malformed file name).
   """
+  @spec invalid_argument :: t
   def invalid_argument, do: 3
 
   @doc """

  @doc """
  Not an error; returned on success.
  """
  def ok, do: 0

  @doc """
  The operation was cancelled (typically by the caller).
  """
  def cancelled, do: 1

  @doc """


  E.g., seeking or reading past end of file.
  """
  @spec out_of_range :: t
  def out_of_range, do: 11

  @doc """
  Operation is not implemented or not supported/enabled in this service.
  """
  @spec unimplemented :: t
  def unimplemented, do: 12

  @doc """
