Use Literal types in calendar, add __all__ (#6827)

stdlib/calendar.pyi

@@ -2,6 +2,34 @@ import datetime
 import sys
 from time import struct_time
 from typing import Any, Iterable, Optional, Sequence
+from typing_extensions import Literal
+
+__all__ = [
+    "IllegalMonthError",
+    "IllegalWeekdayError",
+    "setfirstweekday",
+    "firstweekday",
+    "isleap",
+    "leapdays",
+    "weekday",
+    "monthrange",
+    "monthcalendar",
+    "prmonth",
+    "month",
+    "prcal",
+    "calendar",
+    "timegm",
+    "month_name",
+    "month_abbr",
+    "day_name",
+    "day_abbr",
+    "Calendar",
+    "TextCalendar",
+    "HTMLCalendar",
+    "LocaleTextCalendar",
+    "LocaleHTMLCalendar",
+    "weekheader",
+]
 
 _LocaleType = tuple[Optional[str], Optional[str]]
 
@@ -105,13 +133,12 @@ day_abbr: Sequence[str]
 month_name: Sequence[str]
 month_abbr: Sequence[str]
 
-# Below constants are not in docs or __all__, but enough people have used them
-# they are now effectively public.
+MONDAY: Literal[0]
+TUESDAY: Literal[1]
+WEDNESDAY: Literal[2]
+THURSDAY: Literal[3]
+FRIDAY: Literal[4]
+SATURDAY: Literal[5]
+SUNDAY: Literal[6]
 
-MONDAY: int
-TUESDAY: int
-WEDNESDAY: int
-THURSDAY: int
-FRIDAY: int
-SATURDAY: int
-SUNDAY: int
+EPOCH: Literal[1970]