I had a Method Finder open. I searched for:

{ 1 . 2 . 3 . 4 } . 2 .  2

Then I clicked on the answer that read:

{1. 2. 3. 4} at: 2 --> 2

And I got this walkback.

30 April 2002 3:24:11 pm

VM: unix - Squeak3.2gamma of 15 January 2002 [latest update: #4843]
Image: Squeak3.2gamma [latest update: #4843]

SmallInteger(Object)>>doesNotUnderstand:
	Receiver: 1
	Arguments and temporary variables: 
		aMessage: 	a Message with selector: #includes: and arguments: #($:)
	Receiver's instance variables: 
1

SelectorBrowser>>selectedMessageName
	Receiver: a SelectorBrowser
	Arguments and temporary variables: 
		example: 	'{1. 2. 3. 4} at: 2 --> 2'
		tokens: 	#(#{ 1 #. 2 #. 3 #. 4 #} #at: 2 #- #-> 2)
		aSymbol: 	nil
	Receiver's instance variables: 
		dependents: 	#(a SystemWindow(1) a PluggableTextMorph(3349) a
PluggableListMorph...etc...
		contents: 	a Text for '{ 1 . 2 . 3 . 4 } . 2 .  2'
		selectorIndex: 	2
		selectorList: 	an OrderedCollection('{1. 2. 3. 4} addIfNotPresent: 2
--> 2' '{1....etc...
		classListIndex: 	0
		classList: 	#()

SelectorBrowser>>messageListIndex:
	Receiver: a SelectorBrowser
	Arguments and temporary variables: 
		anInteger: 	2
	Receiver's instance variables: 
		dependents: 	#(a SystemWindow(1) a PluggableTextMorph(3349) a
PluggableListMorph...etc...
		contents: 	a Text for '{ 1 . 2 . 3 . 4 } . 2 .  2'
		selectorIndex: 	2
		selectorList: 	an OrderedCollection('{1. 2. 3. 4} addIfNotPresent: 2
--> 2' '{1....etc...
		classListIndex: 	0
		classList: 	#()

PluggableListMorph>>changeModelSelection:
	Receiver: a PluggableListMorph(2654)
	Arguments and temporary variables: 
		anInteger: 	2
	Receiver's instance variables: 
		bounds: 	283 at 260 corner: 650 at 609
		owner: 	a SystemWindow(1)
		submorphs: 	#(a ScrollBar(2344) a TransformMorph(2769))
		fullBounds: 	283 at 260 corner: 650 at 609
		color: 	Color transparent
		extension: 	a MorphExtension (936) [locked]  [other:  (layoutFrame ->
a LayoutFr...etc...
		borderWidth: 	2
		borderColor: 	#inset
		model: 	a SelectorBrowser
		slotName: 	nil
		open: 	false
		pinSpecs: 	nil
		scrollBar: 	a ScrollBar(2344)
		scroller: 	a TransformMorph(2769)
		retractableScrollBar: 	false
		scrollBarOnLeft: 	false
		getMenuSelector: 	#selectorMenu:
		getMenuTitleSelector: 	#selectorMenuTitle
		scrollBarHidden: 	nil
		hasFocus: 	false
		list: 	an OrderedCollection('{1. 2. 3. 4} addIfNotPresent: 2 --> 2'
'{1. 2. 3. 4...etc...
		selectedMorph: 	nil
		selection: 	nil
		getListSelector: 	#messageList
		getIndexSelector: 	#messageListIndex
		setIndexSelector: 	#messageListIndex:
		keystrokeActionSelector: 	#messageListKey:from:
		autoDeselect: 	true
		font: 	a StrikeFont(Arial 15)
		lastKeystrokeTime: 	0
		lastKeystrokes: 	''
		lastClickTime: 	nil
		doubleClickSelector: 	nil
		potentialDropMorph: 	nil

--- The rest of the stack ---
PluggableListMorph>>setSelectedMorph:
PluggableListMorph>>mouseUp:
PluggableListMorph(Morph)>>handleMouseUp:
MouseButtonEvent>>sentTo:
PluggableListMorph(Morph)>>handleEvent:
PluggableListMorph(Morph)>>handleFocusEvent:
[] in HandMorph>>sendFocusEvent:to:clear:
PasteUpMorph>>becomeActiveDuring:
HandMorph>>sendFocusEvent:to:clear:
HandMorph>>sendEvent:focus:clear:
HandMorph>>sendMouseEvent:
HandMorph>>handleEvent:
HandMorph>>processEvents
[] in WorldState>>doOneCycleNowFor:
Array(SequenceableCollection)>>do:
WorldState>>handsDo:
WorldState>>doOneCycleNowFor:
WorldState>>doOneCycleFor:
PasteUpMorph>>doOneCycle
[] in Project class>>spawnNewProcess
[] in BlockContext>>newProcess