A new version of Collections was added to project The Inbox:
http://source.squeak.org/inbox/Collections-cbc.604.mcz

==================== Summary ====================

Name: Collections-cbc.604
Author: cbc
Time: 6 March 2015, 3:44:37.262 pm
UUID: 0513e699-e650-2340-8505-70e368dd9c64
Ancestors: Collections-eem.603, Collections-cbc.582

Changes to support adding and subtracting strings from DateAndTimes.  Supports syntax such as:
DateAndTime now + '02:00:00:00'
and 
DateAndTime now - '02:00:00:00'

=============== Diff against Collections-eem.603 ===============

Item was added:
+ ----- Method: String>>addToDateTime: (in category 'arithmetic') -----
+ addToDateTime: aDateAndTime
+ 	"Utilized when adjusting DateAndTimes.  Such as:
+ 		DateAndTime now + '02: 00:00:00'
+ 	Not expected to be used outside of that system."
+ 	^self asDuration addToDateTime: aDateAndTime
+ !

Item was added:
+ ----- Method: String>>subtractFromDateTime: (in category 'arithmetic') -----
+ subtractFromDateTime: aDateAndTime
+ 	"Utilized when adjusting DateAndTimes.  Such as:
+ 		DateAndTime now - '02: 00:00:00'
+ 	Not expected to be used outside of that system."
+ 	^self asDuration subtractFromDateTime: aDateAndTime
+ !