   @moduledoc ~S"""
   A String in Elixir is a UTF-8 encoded binary.
 
-  ## Codepoints and graphemes
+  ## Codepoints and grapheme cluster
 
   The functions in this module act according to the Unicode
   Standard, version 6.3.0.


  Graphemes can also be two characters that are interpreted
  as one by some languages. For example, some languages may
  consider "ch" as a grapheme. However, since this information
  depends on the locale, it is not taken into account by this
  module.

  In general, the functions in this module rely on the Unicode
  Standard, but do not contain any of the locale specific behaviour.

      iex> String.length("é")
      1

  Furthermore, this module also presents the concept of grapheme cluster
  (from now on referenced as graphemes). Graphemes can consist of multiple
  codepoints that may be perceived as a single character by readers. For
  example, "é" can be represented either as a single "e with acute" codepoint
  or as the letter "e" followed by a "combining acute accent" (two codepoints):

      iex> string = "\u0065\u0301"
      iex> byte_size(string)
