--- a/PPContextMemento.st	Wed Jul 24 21:13:30 2019 +0000
+++ b/PPContextMemento.st	Wed Jun 10 21:33:27 2020 +0100
@@ -34,12 +34,12 @@
 !
 
 keysAndValuesDo: aBlock
-	properties ifNil: [ ^ self ].
+	properties isNil ifTrue: [ ^ self ].
 	properties keysAndValuesDo: [ :key :value | aBlock value: key value: value copy ] 
 !
 
 propertiesSize
-	properties ifNil: [ ^ 0 ].
+	properties isNil ifTrue: [ ^ 0 ].
 	^ properties size.
 !
 
@@ -71,7 +71,7 @@
 propertyAt: aKey put: anObject
 	"Set the property at aKey to be anObject. If aKey is not found, create a new entry for aKey and set is value to anObject. Answer anObject."
 
-	^ (properties ifNil: [ properties := Dictionary new: 1 ])
+	^ (properties isNil ifTrue: [ properties := Dictionary new: 1 ])
 		at: aKey put: (anObject copy)
 !