code: def _chk_docunknown(args, exp):
          
          unknown = []
          for arg in args:
              if arg[:2] == '--':
                  val = arg[2:]
                  if val not in exp:
                      unknown.append(arg)
              elif arg[:1] == '-':
                  val = arg[1:]
                  if val not in exp:
                      unknown.append(arg)
          if '-h' in unknown or '--help' in unknown:
              return []
          return unknown
docs: Return any unknown args.