--- esT.py-	2016-09-09 23:00:00.000000000 +0900
+++ esT.py	2016-09-09 23:20:00.000000000 +0900
@@ -164,6 +164,8 @@ def tree_op(lst, ops):
 		e1 = lst[1]
 		(k1, v1) = e1[:2]
 		if k1 == 'op':
+			if v1 in [ '++', '--' ]:  # !!!
+				return [ [ k1, (v1, 'back'), e ] ] + tree_op( lst[2:], ops )
 			return tree_op2(lst, ops, e, k1, v1)
 
 	return [ e ] + tree_op( lst[1:], ops )
@@ -332,6 +334,12 @@ def do_op1(v, a, info):
 		return do_set(oa, a+1, info)
 	if v == '--':
 		return do_set(oa, a-1, info)
+	if v == ('++', 'back'):
+		do_set(oa, a+1, info)
+		return a
+	if v == ('--', 'back'):
+		do_set(oa, a-1, info)
+		return a
 
 	warn_no_sup('do_op1', 'v', v)