fix doctest

dokos.py

@@ -88,7 +88,8 @@ def batched(iterable, count):
     '''
     if count < 1:
         raise ValueError('n must be at least one')
-    while (batch := tuple(islice(iter(iterable), count))):
+    iterable = iter(iterable)
+    while (batch := tuple(islice(iterable, count))):
         yield batch