       ""
 
   """
+  @spec extname(t) :: binary
   def extname(path) do
     FN.extension(String.from_char_data!(path))
   end

  directory. If, for some reason, the current working directory
  cannot be retrieved, returns the full path.
  """
  def relative_to_cwd(path) do
    case :file.get_cwd do
      { :ok, base } -> relative_to(path, String.from_char_data!(base))

      "/foo/bar"

  """
  @spec join([t]) :: binary
  def join([name1, name2|rest]), do:
    join([join(name1, name2)|rest])
  def join([name]), do:
