def parse(args: List[str]) -> Tuple[str, List[int]]: arguments = collections.deque(args) separator = "\n" operands: List[int] = [] while arguments: arg = arguments.popleft() if not operands: if arg == "--help": print(USAGE) sys.exit(0) if arg in ("-s", "--separator"): separator = arguments.popleft() continue try: operands.append(int(arg)) except ValueError: raise SystemExit(USAGE) if len(operands) > 3: raise SystemExit(USAGE) return separator, operands