@classmethod
    def find_or_create_by_key(cls, migration_key):
        raise NotImplementedError('Abstract Class')
Return the root directory for an instance.
dataset/ETHPy150Open monarch-org/monarch/monarch/models.py/MigrationHistoryStorage.find_or_create_by_key--crossover with--dataset/ETHPy150Open ganeti/ganeti/lib/hypervisor/hv_chroot.py/ChrootManager._InstanceDir