code: def _normalize_file_paths(self, *args):
          
          paths = []
          for arg in args:
              if arg is None:
                  continue
              elif self._is_valid_file(arg):
                  paths.append(arg)
              elif isinstance(arg, list) and all(self._is_valid_file(_) for _ in arg):
                  paths = paths + arg
              elif not self.ignore_errors:
                  raise TypeError('Config file paths must be string path or list of paths!')
          return paths
docs: Returns all given configuration file paths as one list.