def render(svg, options = {})
      # #current_points = points.dup

      @scaler = 1
      total = 0
      
      layers.each do |layer|
        total += layer.sum_values
      end 
      
      @scaler = 100.0 / total
      
      @percent_used = 30
      
      layers.each do |layer|
        layer_options = options.dup
        layer_options = layer_options.merge(@options)
        layer_options = layer_options.merge(layer.options)
        layer_options[:scaler] = @scaler
        layer_options[:percent_used] = @percent_used
        @percent_used += @scaler * layer.sum_values
        layer_options[:color] = layer.preferred_color || layer.color || options[:theme].next_color          
        
        layer.render(svg, layer_options)
      end
    end
def render(svg, options = {})
      # #current_points = points.dup

      @scaler = 1
      total = 0
      
      layers.each do |layer|
        total += layer.sum_values
      end 
      
      @scaler = 100.0 / total
      
      @percent_used = 30
      
      layers.each do |layer|
        layer_options = options.dup
        layer_options = layer_options.merge(@options)
        layer_options = layer_options.merge(layer.options)
        layer_options[:scaler] = @scaler
        layer_options[:percent_used] = @percent_used
        @percent_used += @scaler * layer.sum_values
        layer_options[:color] = layer.preferred_color || layer.color || options[:theme].next_color          
        
        layer.render(svg, layer_options)
      end
    end
The initialize method passes itself to the block, and since Pie is a
 LayerContainer, layers (pie slice) can be added just as if they were being
 added to Graph.
 Overrides Base#render to fiddle with layers' points to achieve a stacked
 effect.