 
   getYStack: (type, group, x, seriesId, start = 0) ->
     allSeries = @series()
-    xscaletype = @x.scaleType()
-    yscaledomainmin = @yScale.domainMin
+    xScaleType = @x.scaleType()
+    yScaleDomainMin = @yScale.domainMin
 
     if group
-      yStack = Math.max(yscaledomainmin, 0)
+      yStack = Math.max(yScaleDomainMin, 0)
       maybeys = allSeries.map (series) ->
         if series._.seriesId < seriesId and series.group() == group and series._.type == type
-          series.getY(x, xscaletype is 'discrete')
+          series.getY(x, xScaleType is 'discrete')
       yStack + hx.sum maybeys.filter hx.identity
     else
       Math.max(start, 0)

        else
          allX = hx.unique hx.flatten series.map (s) -> s.data().map ({ x }) -> x
          stackHeights = allX.map (x) ->
            maybeys = series.map (series) -> series.getY x, xscaletype is 'discrete'
            hx.sum maybeys.filter hx.identity
          {
            yymin: hx.min stackHeights

    # The series must already be tagged before calling this method
    # XXX: band series?
    allSeries = @series()
    xScaleType = @x.scaleType()

    initValue = { ymin: 0, ymax: 0 }
    types = hx.groupBy(allSeries, (d) -> d._.type)
