<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def key_values_cache_key_name(cls, *key_fields):
 """ Key for fetching unique key values from the cache """

        key_fields = key_fields or cls.KEY_FIELDS
        return 'configuration/{}/key_values/{}'.format(cls.__name__, ','.join(key_fields))