'Snapshots volumes attached to a specified instance.
The counter action to this is :func:`volume_snapshot_delete`
:param nova.context.RequestContext context:
The security context.
:param nova.objects.instance.Instance  instance:
The instance that has the volume attached
:param uuid volume_id:
Volume to be snapshotted
:param create_info: The data needed for nova to be able to attach
to the volume.  This is the same data format returned by
Cinder\'s initialize_connection() API call.  In the case of
doing a snapshot, it is the image file Cinder expects to be
used as the active disk after the snapshot operation has
completed.  There may be other data included as well that is
needed for creating the snapshot.'

def volume_snapshot_create(self, context, instance, volume_id, create_info):

    raise NotImplementedError()
