def and_list(items):
  """ Create a comma-separated list of strings.
  """
  assert isinstance(items, list)
  match len(items):
    case 0: return ''
    case 1: return items[0]
    case 2: return f'{items[0]} and {items[1]}'
    case _: return ', '.join(items[0:-1]) + f', and {items[-1]}'