def rectangle(upper_left_x, upper_left_y, lower_right_x, lower_right_y)
      primitive 'rectangle ' + format('%g,%g %g,%g',
                                      upper_left_x, upper_left_y, lower_right_x, lower_right_y)
    end
def rectangle(upper_left_x, upper_left_y, lower_right_x, lower_right_y)
      primitive 'rectangle ' + format('%g,%g %g,%g',
                                      upper_left_x, upper_left_y, lower_right_x, lower_right_y)
    end
Draw a rectangle