code: def check_input(self, token):
          
          if isinstance(token.payload, Instance):
              return
          raise Exception(self.full_name + ": Unhandled data type: " + str(token.payload.__class__.__name__))
docs: Performs checks on the input token. Raises an exception if unsupported.
  
          :param token: the token to check
          :type token: Token