Introduce #isEmail

Author: koendehondt

src/CodeOfSpec20Book/Email.class.st

@@ -84,6 +84,12 @@ Email >> isDraft [
 	^ status = #draft
 ]
 
+{ #category : 'testing' }
+Email >> isEmail [
+
+	^ true
+]
+
 { #category : 'testing' }
 Email >> isReceived [
 

src/CodeOfSpec20Book/MailClientPresenterWithTransmissions.class.st

@@ -0,0 +1,10 @@
+"
+My superclasses use traditional means to connect presenters. I use transmissions.
+"
+Class {
+	#name : 'MailClientPresenterWithTransmissions',
+	#superclass : 'MailClientPresenterWithDecorations',
+	#category : 'CodeOfSpec20Book-Chapter14',
+	#package : 'CodeOfSpec20Book',
+	#tag : 'Chapter14'
+}

src/CodeOfSpec20Book/MailFolder.class.st

@@ -47,6 +47,12 @@ MailFolder >> initialize [
 	emails := OrderedCollection new
 ]
 
+{ #category : 'testing' }
+MailFolder >> isEmail [
+
+	^ false
+]
+
 { #category : 'private - accessing' }
 MailFolder >> name: aString [