anchor.diff:  
   ##
   # HistogramData
  -# Doesn't render anything. Memoizes computation of Histogram data. 
  +# Doesn't render anything. Stores computed Histogram data. 
   HistogramData = ReactiveComponent
     displayName: 'HistogramData'
   
  
positive.code:     opinions = @data(@proposal).opinions || []
  
      # we only need to recompute this data if the distribution of stances has changed
      memoize_hash = JSON.stringify( _.map(opinions, (o) -> o.stance) )
      if @local.memoize_hash != memoize_hash
        avatar_size = Math.min BIGGEST_POSSIBLE_AVATAR_SIZE, 
          Math.floor(BIGGEST_POSSIBLE_AVATAR_SIZE / Math.sqrt( (opinions.length + 1) / 10 )  )
  
  
negative.code:       segment_data.avatar_size = avatar_size
        save segment_data
  
        @local.last_computation_hash = last_computation_hash
        save @local
  
  
  