Add half of a coder

src/Carp/CarpExpression.class.st

@@ -1,9 +1,22 @@
 Class {
 	#name : #CarpExpression,
 	#superclass : #Object,
+	#instVars : [
+		'documentation'
+	],
 	#category : #'Carp-IDE'
 }
 
+{ #category : #accessing }
+CarpExpression >> documentation [
+	^ documentation ifNil: ['']
+]
+
+{ #category : #accessing }
+CarpExpression >> documentation: aString [
+	documentation := aString
+]
+
 { #category : #converting }
 CarpExpression >> toCarp [
 	^ self subclassResponsibility