def roundrectangle(center_x, center_y, width, height, corner_width, corner_height)
      primitive 'roundrectangle ' + format('%g,%g,%g,%g,%g,%g',
                                           center_x, center_y, width, height, corner_width, corner_height)
    end
def roundrectangle(center_x, center_y, width, height, corner_width, corner_height)
      primitive 'roundrectangle ' + format('%g,%g,%g,%g,%g,%g',
                                           center_x, center_y, width, height, corner_width, corner_height)
    end
Draw a rectangle with rounded corners