def axes=(axes)
      idx = 0
      @axes, @axis_labels, @axis_ranges = [], [], []
      [:x, :y, :r, :t].each do |axis|
        case axes[axis]
        when Array
          @axis_labels << ("#{idx}:|" + axes[axis].map {|l| CGI::escape(l.to_s) }.join('|'))
          @axes << axis
          idx += 1
        when Range
          @axis_ranges << ("#{idx},#{axes[axis].first},#{axes[axis].last}")
          @axes << axis
          idx += 1
        when true
          @axes << axis
          idx += 1
        end
      end
    end
def axes=(axes)
      idx = 0
      @axes, @axis_labels, @axis_ranges = [], [], []
      [:x, :y, :r, :t].each do |axis|
        case axes[axis]
        when Array
          @axis_labels << ("#{idx}:|" + axes[axis].map {|l| CGI::escape(l.to_s) }.join('|'))
          @axes << axis
          idx += 1
        when Range
          @axis_ranges << ("#{idx},#{axes[axis].first},#{axes[axis].last}")
          @axes << axis
          idx += 1
        when true
          @axes << axis
          idx += 1
        end
      end
    end
TODO: Add support for axis label positions/styles, support for multiple label sets per axis