def quarter_circle(center, options)
      case options[:quadrant]
      when 1
        start_angle = 0
        end_angle = 90
      when 2
        start_angle = 90
        end_angle = 180
      when 3
        start_angle = 180
        end_angle = 270
      when 4
        start_angle = 270
        end_angle = 360
      end
      pie_slice(center,
                :radius => options[:radius],
                :start_angle => start_angle,
                :end_angle => end_angle,
                :stroke_both_sides => options[:stroke_both_sides])
    end
def quarter_circle(center, options)
      case options[:quadrant]
      when 1
        start_angle = 0
        end_angle = 90
      when 2
        start_angle = 90
        end_angle = 180
      when 3
        start_angle = 180
        end_angle = 270
      when 4
        start_angle = 270
        end_angle = 360
      end
      pie_slice(center,
                :radius => options[:radius],
                :start_angle => start_angle,
                :end_angle => end_angle,
                :stroke_both_sides => options[:stroke_both_sides])
    end
options must include :radius and :quadrant
 quadrant is 1, 2, 3, or 4
 see pie_slice for explanation of optional
 :stroke_both_sides option