'Return snapshot ID for particular volume.'

def _get_snap_id(self, cg_name, snap_name):

    xml_tree = self.vpsa.send_cmd('list_vol_snapshots', cg_name=cg_name)
    snap = self._xml_parse_helper(xml_tree, 'snapshots', ('display-name', snap_name))
    if (snap is not None):
        return snap.findtext('name')
    return None
