<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _shrink_dict(self, shrink):
 """ Shrink dict down to essentials :param shrink: Dict to shrink :type shrink: dict :return: Shrunk dict :rtype: dict """

        res = {}

        if len(shrink.keys()) == 1 and "value" in shrink:
            return self.shrink(shrink['value'])
        else:
            for a in shrink:
                res[a] = self.shrink(shrink[a])

                if not res[a]:
                    del res[a]
        return res