#include <Servo.h>
Servo myservo;

int pos = 0;

void setup() {
  myservo.attach(9);
}

void loop() {
  for (pos = 0; pos <= 180; pos +=1){
  myservo.write(pos);
  delay(10);}
  for (pos = 180; pos >= 0; pos -=1){
  myservo.write(pos);
  delay(10);}
}