diff --git a/Socialmetrica.package/TweetsCollection.class/instance/timeSpan.st b/Socialmetrica.package/TweetsCollection.class/instance/timeSpan.st
new file mode 100644
index 0000000..96b3c46
--- /dev/null
+++ b/Socialmetrica.package/TweetsCollection.class/instance/timeSpan.st
@@ -0,0 +1,4 @@
+accessing
+timeSpan
+
+	^ Timespan starting: self oldest created ending: self newest created
\ No newline at end of file
diff --git a/Socialmetrica.package/TweetsCollection.class/instance/timeSpansByDays.st b/Socialmetrica.package/TweetsCollection.class/instance/timeSpansByDays.st
index 0501c48..d144494 100644
--- a/Socialmetrica.package/TweetsCollection.class/instance/timeSpansByDays.st
+++ b/Socialmetrica.package/TweetsCollection.class/instance/timeSpansByDays.st
@@ -1,5 +1,4 @@
 accessing
 timeSpansByDays
 
-	^ (Timespan starting: self oldest created ending: self newest created) 
-			dates asOrderedCollection collect: [ :date | Timespan starting: date ending: date + 24 hours]
\ No newline at end of file
+	^ self timeSpan dates asOrderedCollection collect: [ :date | Timespan starting: date ending: date + 24 hours]
\ No newline at end of file
diff --git a/Socialmetrica.package/TweetsCollection.class/instance/timeSpansByWeeks.st b/Socialmetrica.package/TweetsCollection.class/instance/timeSpansByWeeks.st
index af397f8..b9e521e 100644
--- a/Socialmetrica.package/TweetsCollection.class/instance/timeSpansByWeeks.st
+++ b/Socialmetrica.package/TweetsCollection.class/instance/timeSpansByWeeks.st
@@ -1,5 +1,4 @@
 accessing
 timeSpansByWeeks
 
-	^ (Timespan starting: self oldest created ending: self newest created) 
-			weeks asOrderedCollection
\ No newline at end of file
+	^ self timeSpan weeks asOrderedCollection
\ No newline at end of file