Alternate between two positions before stopping.
Alternate between two positions of Servo A, on repeat 10 times before stopping.
for (let index = 0; index < 10; index++) {
    sb.setServoPosition(sb.servo(SBServo.ServoA), 20)
    basic.pause(1000)
    sb.setServoPosition(sb.servo(SBServo.ServoA), 80)
    basic.pause(1000)
}If using micro:bit for the first time, follow this setup.