accessing
exportTweetsHistogramWithBars: aNumberOfBars

	| tweetsByTimeSpan subtotals tweetsColor x tweetsHistogram diagram |

	tweetsByTimeSpan := self collectMessages: [ self tweets] byTimeSpanSplits: aNumberOfBars.
	subtotals := tweetsByTimeSpan values collect: [ :collection | collection size ].
	tweetsColor := (Color r:(91/255) g:(131/255) b:(222/255)).
	x := 1 to: subtotals size.
	tweetsHistogram := RSChart new.
	tweetsHistogram extent: 800@200.
	diagram := RSBarPlot new x: x y:subtotals.
	diagram color: tweetsColor.
	tweetsHistogram addPlot: diagram.
	tweetsHistogram addDecoration: (RSHorizontalTick new
    	fromNames: tweetsByTimeSpan keys;
    	labelRotation: 0;
		fontSize: 80 /aNumberOfBars;
    	yourself).
    tweetsHistogram addDecoration: (RSVerticalTick new 
		integer;
		fontSize: 80 /aNumberOfBars).
	tweetsHistogram build.
	tweetsHistogram canvas pdfExporter 
		zoomToShapes;
		noFixedShapes; 
		fileName: (self folder / 'trinos.pdf')fullName;
		export.	
	^ self folder / 'trinos.pdf'