#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(15); 
}
for (pos = 180; pos >= 0; pos -= 1) { 
myservo.write(pos); 
delay(15); 
}
}