code: def norm_join(prefix, suffix):
      
      if (prefix is None) and (suffix is None):
          return "."
      if prefix is None:
          return os.path.normpath(suffix)
      if suffix is None:
          return os.path.normpath(prefix)
      return os.path.normpath(os.path.join(prefix, suffix))
docs: Join ``prefix`` and ``suffix`` paths
      and return the resulting path, normalized.
  
      :param string prefix: the prefix path
      :param string suffix: the suffix path
      :rtype: string