       iex> String.next_grapheme("olá")
       {"o", "lá"}
 
+      iex> String.next_grapheme("")
+      nil
+
   """
   @spec next_grapheme(t) :: {grapheme, t} | nil
   def next_grapheme(binary) do

      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.first("եոգլի")
      "ե"

      iex> String.first("")
      nil

  """
  @spec first(t) :: grapheme | nil
