code: def clone(self, source_id, backup_id, size,
                volume_id=None, source_host=None):
          
          volume_id = volume_id or str(uuid.uuid4())
          return self.http_put('/volumes/%s' % volume_id,
                               params=self.unused({
                                   'source_host': source_host,
                                   'source_volume_id': source_id,
                                   'backup_id': backup_id,
                                   'size': size
                               }))
docs: create a volume then clone the contents of
          the backup into the new volume