 
       iex> String.first("եոգլի")
       "ե"
+
+      iex> String.first("")
+      nil
 
   """
   @spec first(t) :: grapheme | nil

      iex> String.next_grapheme_size("olá")
      {1, "lá"}

  """
  @spec next_grapheme_size(t) :: {pos_integer, t} | nil
  defdelegate next_grapheme_size(string), to: String.Unicode

      iex> String.next_grapheme("olá")
      {"o", "lá"}

      iex> String.next_grapheme("")
      nil

  """
  @spec next_grapheme(t) :: {grapheme, t} | nil
  def next_grapheme(binary) do
