def read_configs_(self):
        """Read config files and set config values accordingly.

        Returns:
            (dict, list, list): respectively content of files, list of
            missing/empty files and list of files for which a parsing error
            arised.
        """
        if not self.config_files_:
            return {}, [], []
        content = {section: {} for section in self}
        empty_files = []
        faulty_files = []
        for cfile in self.config_files_:
            conf_dict = self.read_config_(cfile)
            if conf_dict is None:
                faulty_files.append(cfile)
                continue
            elif not conf_dict:
                empty_files.append(cfile)
                continue
            for section, secdict in conf_dict.items():
                content[section].update(secdict)
        return content, empty_files, faulty_files
Read config files and set config values accordingly.

        Returns:
            (dict, list, list): respectively content of files, list of
            missing/empty files and list of files for which a parsing error
            arised.