【EV3 Discovery 108】往上数和往下数

你能编写程序，用一个变量记录ev3的左键和右键被按下的次数吗？如果按下右键，变量值加1；如果你按下左键，变量值减1。在ev3显示屏上显示该变量值。

from pybricks import ev3brick as brick
from pybricks.ev3devices import (Motor, TouchSensor, ColorSensor,
                                 InfraredSensor, UltrasonicSensor, GyroSensor)
from pybricks.parameters import (Port, Stop, Direction, Button, Color,
                                 SoundFile, ImageFile, Align)
from pybricks.tools import print, wait, StopWatch
from pybricks.robotics import DriveBase

# Write your program here

brick.sound.beep()
num = 0
while True:
    if Button.LEFT in brick.buttons():
        num = num - 1
    if Button.RIGHT in brick.buttons():
        num= num + 1
    brick.display.clear()
    brick.display.text(num, (60, 50))
    wait(100)