added constant per type of availability

smash/web/models/constants.py

@@ -78,9 +78,12 @@ WEEKDAY_CHOICES = (
     (SUNDAY_AS_DAY_OF_WEEK, 'SUNDAY'),
 )
 
+AVAILABILITY_HOLIDAY = 'H'
+AVAILABILITY_EXTRA = 'X'
+
 AVAILABILITY_CHOICES = (
-    ('H', 'Holiday'),
-    ('X', 'Extra Availability'),
+    (AVAILABILITY_HOLIDAY, 'Holiday'),
+    (AVAILABILITY_EXTRA, 'Extra Availability'),
 )
 
 REDCAP_TOKEN_CONFIGURATION_TYPE = "REDCAP_TOKEN_CONFIGURATION_TYPE"