diff --git a/src/punctuation/check.py b/src/punctuation/check.py
index 9e7ea4b..ba1a0fd 100755
--- a/src/punctuation/check.py
+++ b/src/punctuation/check.py
@@ -1,6 +1,8 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
+from itertools import product
+
 punctuationPairs = [
     ('‘', '’'),
     ('“', '”'),
@@ -9,36 +11,31 @@ punctuationPairs = [
 ]
 
 
-def pairsCheck(sentence: str) -> (bool, str):
+def pairsCheck(sentence: str) -> bool:
+    errorFlag = False
     punctuationStack = []
     sentence = list(sentence)
 
     def colorful(char: str, color: int) -> str:  # string with color
         return '\033[0;%dm%s\033[0;39m' % (color, char)
 
-    errorFlag = False
-    for i in range(0, len(sentence)):
-        for punctuationPair in punctuationPairs:
-            if sentence[i] == punctuationPair[0]:  # get left punctuation
-                punctuationStack.append(punctuationPair)
+    for (i, punctuationPair) in product(range(0, len(sentence)), punctuationPairs):
+        if sentence[i] == punctuationPair[0]:  # get left punctuation
+            punctuationStack.append(punctuationPair)
+            sentence[i] = colorful(sentence[i], 33)  # mark punctuation
+        elif sentence[i] == punctuationPair[1]:  # get right punctuation
+            if punctuationStack.pop()[1] != sentence[i]:
+                errorFlag = True
+                sentence[i] = colorful(sentence[i], 31)  # match error case
+            else:
                 sentence[i] = colorful(sentence[i], 33)  # mark punctuation
-                break
-            elif sentence[i] == punctuationPair[1]:  # get right punctuation
-                if punctuationStack.pop()[1] != sentence[i]:
-                    errorFlag = True
-                    sentence[i] = colorful(sentence[i], 31)  # match error case
-                else:
-                    sentence[i] = colorful(sentence[i], 33)  # mark punctuation
-                break
-    if len(punctuationStack) == 0 and not errorFlag:
-        return True, ''.join(sentence)  # no error in sentence
-
-    for punctuation in reversed(punctuationStack):
-        sentence.append(colorful(punctuation[1], 35))
-        # print(punctuation)
-    return False, ''.join(sentence)
-
-
-status, ret = pairsCheck('测试“这个是OK的《2333》没错‘233’’《嗯嗯')
-print('ok' if status else 'error')
-print(ret)
+
+    if len(punctuationStack) != 0 or errorFlag:  # something error in sentence
+        for punctuation in reversed(punctuationStack):  # replenish missing punctuation
+            sentence.append(colorful(punctuation[1], 35))
+        print(''.join(sentence))
+        return False
+    return True  # no error match in sentence
+
+
+pairsCheck('测试“这个是OK的《2333》没错‘233’嗯嗯”')