#include <Servo.h>
Servo myServo;

void setup(){
myServo.attach(9);
}
void loop () {
for (int angle = 0; angle <= 180; angle++) {
  myServo.write(angle);
  delay(15);
}

for (int angle = 180; angle >= 0; angle--) {
  myServo.write(angle);
  delay(15);
}
}