#include <Servo.h>

Servo myservo;

int pos = 0;
int speed_servo = 15;

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

void loop(){
for (pos = 0; pos <= 180; pos += 1) {
myservo.write(pos);
delay(15);
}
for (pos = 180; pos >= 0; pos -= 1) {
myservo.write(pos);
delay(15);
}
}