   end
 
   @doc """
-  Returns a string with the option's description. Raises if `name` is not a
-  known option.
+  Returns a string with the option's description. Raises `ArgumentError` 
+  if `name` is not a known option.
   """
   def help(name) do
     if name in @supported_options do

  @doc """
  Sets the value for the option `name` to `value`.

  Returns option's previous value in the case of success.

  If `name` is not a known option or if the value is invalid, raises
  ArgumentError.
  """
  def set(name, value)


  end

  @doc """
  Get current value of the option `name`. Raises `ArgumentError` if `name` is not a
  known option.
  """
  def get(name)
