parses an MMAX base file (``*.mmax``) and returns the path
        to the corresponding ``_words.xml`` file (which contains
        the tokens of the document).

def get_word_file(self, mmax_base_file):
        """
        parses an MMAX base file (``*.mmax``) and returns the path
        to the corresponding ``_words.xml`` file (which contains
        the tokens of the document).
        """
        return os.path.join(self.mmax_project.paths['project_path'],
                            self.mmax_project.paths['basedata'],
                            etree.parse(mmax_base_file).find('//words').text)