<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_iss(self, key):
 """ Get the Issuer ID :param key: Key to the information in the state database :return: The issuer ID """

        _state = self.get_state(key)
        if not _state:
            raise KeyError(key)
        return _state['iss']