         normalise_month month_integer
     end
   end
-  def normalise_month(month) when month > 0 and month < 13, do: month
-  def normalise_month(_), do: :nil
+
+  def normalise_month(month) when month > 0 and month < 13,
+    do: month
+  def normalise_month(_),
+    do: :nil
 
 
   @doc """

    """
    @spec is_valid?(DateTuple.t) :: boolean
    def is_valid?(date_tuple)
    def is_valid?(%DateTuple{month: month}) when is_nil(month), do: false
    def is_valid?(%DateTuple{year: year}) when is_nil(year), do: false
    def is_valid?(date_tuple=%DateTuple{day: day}) when is_nil(day) do
      is_valid? Map.put(date_tuple, :day, 1)
    end
    def is_valid?(%DateTuple{year: year, month: month, day: day}) do
      case Date.new(year, month, day) do
        {:ok, _} ->

  """
  @spec normalise_day(String.t | integer) :: 1..31 | :nil
  def normalise_day(day)
  def normalise_day(""),
    do: :nil

  def normalise_day(day) when is_binary(day) do
    normalise_day String.to_integer day
  end

  def normalise_day(day) when day > 0 and day < 32,
    do: day
  def normalise_day(_),
    do: :nil 


  @doc """
