def characters(self, string, segment_separator=' ', separator=' # ',):
        """
        Given a string as input, return a space-delimited string of Unicode characters
        (code points rendered as glyphs).
        Parameters
        ----------
        string : str
            A Unicode string to be tokenized into graphemes.
        Returns
        -------
        result : str
            String returned is space-delimited on Unicode characters and contains "#" to
            mark word boundaries.
            The string is in NFD.
        Notes
        -----
        Input is first normalized according to Normalization Ford D(ecomposition).
        String returned contains "#" to mark word boundaries.
        """
        return separator.join(segment_separator.join(word) for word in nfd(string).split())