fix python2 comat

zhdate/__init__.py

@@ -10,7 +10,8 @@
 """
 
 from datetime import datetime, timedelta
-from itertools import accumulate
+
+from .compat import accumulate
 from .constants import CHINESENEWYEAR, CHINESEYEARCODE
 
 

zhdate/compat.py

@@ -0,0 +1,20 @@
+# -*- coding=utf-8 -*-
+
+from __future__ import absolute_import, print_function
+
+import operator
+
+
+def accumulate(iterable, func=operator.add):
+    'Return running totals'
+    # accumulate([1,2,3,4,5]) --> 1 3 6 10 15
+    # accumulate([1,2,3,4,5], operator.mul) --> 1 2 6 24 120
+    it = iter(iterable)
+    try:
+        total = next(it)
+    except StopIteration:
+        return
+    yield total
+    for element in it:
+        total = func(total, element)
+        yield total