>>> store = await ts.KvStore.open({
...     'driver': 'gcs',
...     'bucket': 'my-bucket',
...     'path': 'path/to/object'
... })
>>> store.spec()
KvStore.Spec({'bucket': 'my-bucket', 'driver': 'gcs', 'path': 'path/to/object'})
>>> store.path
'path/to/object'