'Delete the snapshot of a storagegroup.
:param array: the array serial number
:param snap_name: the name of the snapshot
:param source_sg_id: the source device id'

def delete_storagegroup_snap(self, array, snap_name, source_sg_id):

    resource_name = ('%(sg_name)s/snapshot/%(snap_id)s/generation/0' % {'sg_name': source_sg_id, 'snap_id': snap_name})
    return self.delete_resource(array, REPLICATION, 'storagegroup', resource_name)
