code: def one_of(*args):
      
      if len(args) == 1 and isinstance(args[0], list):
          items = args[0]
      else:
          items = list(args)
  
      def validate(value):
          if not value in items:
              return e("{} is not in the list {}", value, items)
      return validate
docs: Validates that a field value matches one of the values
      given to this validator.