             if flatRowKey not of @tree
                 @tree[flatRowKey] = {}
             if flatColKey not of @tree[flatRowKey]
-                @tree[flatRowKey][flatColKey] = @aggregator(this, rowKey, colKey) 
+                @tree[flatRowKey][flatColKey] = @aggregator(this, rowKey, colKey)
             @tree[flatRowKey][flatColKey].push record
 
     getAggregator: (rowKey, colKey) =>

    if not existingOpts? or overwrite
        opts = $.extend defaults, inputOpts
    else
        opts = existingOpts 

    try
        #cache the input in some useful form

        #thanks http://stackoverflow.com/a/12213072/112871
        (record) ->
            date = new Date(Date.parse(record[col]))
            formatString.replace /%(.)/g, (m, p) ->
                switch p
                    when "y" then date.getFullYear()
                    when "m" then zeroPad(date.getMonth()+1)
