   end
 
   defp to_list(tuple) when is_tuple(tuple), do: Tuple.to_list(tuple)
-  defp to_list(list)  when is_list(list),   do: list
+  defp to_list(list) when is_list(list), do: list
 end

      "deep"

  """
  @spec to_string(:unicode.charlist) :: String.t
  def to_string(list) when is_list(list) do
    try do
      :unicode.characters_to_binary(list)

  """
  @spec zip([list]) :: [tuple]
  def zip([]), do: []

  def zip(list_of_lists) when is_list(list_of_lists) do
    do_zip(list_of_lists, [])
  end
