diff --git a/src/FAST-Core-Tools/FASTAbstractVariableVersionSSA.class.st b/src/FAST-Core-Tools/FASTAbstractVariableVersionSSA.class.st
index a7f6a8c..6b784e7 100644
--- a/src/FAST-Core-Tools/FASTAbstractVariableVersionSSA.class.st
+++ b/src/FAST-Core-Tools/FASTAbstractVariableVersionSSA.class.st
@@ -34,6 +34,12 @@ FASTAbstractVariableVersionSSA >> includes: aSSAVersion [
 	^ self ssaVariables includes: aSSAVersion
 ]
 
+{ #category : 'testing' }
+FASTAbstractVariableVersionSSA >> includesVersionOrPhi: aSSAVersionOrPhi [
+
+	^ aSSAVersionOrPhi ssaVariables anySatisfy: [ :variable | self includes: variable ]
+]
+
 { #category : 'testing' }
 FASTAbstractVariableVersionSSA >> isPhi [
 
@@ -61,7 +67,7 @@ FASTAbstractVariableVersionSSA >> localDeclarationName [
 { #category : 'accessing' }
 FASTAbstractVariableVersionSSA >> localUses [
 
-	^ self localDeclaration localUses select: [ :access | access ssaVersion includes: self ]
+	^ self localDeclaration localUses select: [ :access | access ssaVersion includesVersionOrPhi: self ]
 ]
 
 { #category : 'accessing' }
@@ -81,7 +87,19 @@ FASTAbstractVariableVersionSSA >> printOn: aStream [
 	aStream nextPut: $]
 ]
 
+{ #category : 'accessing' }
+FASTAbstractVariableVersionSSA >> readAccesses [
+
+	^ self localUses reject: [ :access | access isVariableWriteAccess ]
+]
+
 { #category : 'accessing' }
 FASTAbstractVariableVersionSSA >> ssaVariables [
 	^ self subclassResponsibility
 ]
+
+{ #category : 'accessing' }
+FASTAbstractVariableVersionSSA >> writeAccesses [
+
+	^ self localUses select: [ :access | access isVariableWriteAccess ]
+]
diff --git a/src/FAST-Core-Tools/FASTPyTCanBeVariable.extension.st b/src/FAST-Core-Tools/FASTPyTCanBeVariable.extension.st
new file mode 100644
index 0000000..086428b
--- /dev/null
+++ b/src/FAST-Core-Tools/FASTPyTCanBeVariable.extension.st
@@ -0,0 +1,13 @@
+Extension { #name : 'FASTPyTCanBeVariable' }
+
+{ #category : '*FAST-Core-Tools' }
+FASTPyTCanBeVariable >> localDeclarationName [
+
+	self explicitRequirement
+]
+
+{ #category : '*FAST-Core-Tools' }
+FASTPyTCanBeVariable >> variableDeclarator [
+
+	self explicitRequirement
+]
diff --git a/src/FAST-Core-Tools/FASTTEntity.extension.st b/src/FAST-Core-Tools/FASTTEntity.extension.st
index 409a3aa..fcbbe76 100644
--- a/src/FAST-Core-Tools/FASTTEntity.extension.st
+++ b/src/FAST-Core-Tools/FASTTEntity.extension.st
@@ -65,6 +65,13 @@ FASTTEntity >> isSameAsCFGCasePattern: aPattern [
 	^ self sourceCode = aPattern sourceCode
 ]
 
+{ #category : '*FAST-Core-Tools' }
+FASTTEntity >> isVariableWriteAccess [
+	"I should be implemented in order to have the SSA working well. I should return false for most nodes, and return true if I represent a node that is a write access for a variable."
+
+	^ self explicitRequirement
+]
+
 { #category : '*FAST-Core-Tools' }
 FASTTEntity >> localDeclaration [
 	"Used for LocalResolver"
@@ -102,6 +109,15 @@ FASTTEntity >> newVersionNumber [
 		  ifNotNil: [ :active | active version + 1 ]
 ]
 
+{ #category : '*FAST-Core-Tools' }
+FASTTEntity >> readAccesses [
+
+	| uses |
+	uses := self attributeAt: #localUses ifAbsent: [ Error signal: 'No local resolution done.' ].
+
+	^ uses reject: #isVariableWriteAccess
+]
+
 { #category : '*FAST-Core-Tools' }
 FASTTEntity >> ssaName [
 	"Used for SSA"
@@ -122,3 +138,12 @@ FASTTEntity >> ssaVersion: aSSAVersion [
 
 	self attributeAt: #ssaVersion put: aSSAVersion
 ]
+
+{ #category : '*FAST-Core-Tools' }
+FASTTEntity >> writeAccesses [
+
+	| uses |
+	uses := self attributeAt: #localUses ifAbsent: [ Error signal: 'No local resolution done.' ].
+
+	^ uses select: #isVariableWriteAccess
+]