Issue #26778: Fixed "a/an/and" typos in code comment and documentation.
diff --git a/Lib/calendar.py b/Lib/calendar.py
index d3bd236..4c95a49 100644
--- a/Lib/calendar.py
+++ b/Lib/calendar.py
@@ -142,7 +142,7 @@
 
     def iterweekdays(self):
         """
-        Return a iterator for one week of weekday numbers starting with the
+        Return an iterator for one week of weekday numbers starting with the
         configured first one.
         """
         for i in range(self.firstweekday, self.firstweekday + 7):