   defdelegate upcase(binary), to: String.Unicode
 
   @doc """
-  Converts all characters on the given string to lowercase.
+  Converts all characters in the given string to lowercase.
 
   ## Examples
 

    {acc, grapheme <> rest}

  @doc """
  Converts all characters on the given string to uppercase.

  ## Examples


  defdelegate next_grapheme(string), to: String.Graphemes

  @doc """
  Returns the first grapheme from a utf8 string,
  `nil` if the string is empty.

  ## Examples
