#include <Servo.h>

Servo myservo;
int servoPin = 9; 

void setup() {
 myservo.attach(servoPin);
}
 
void loop() {
 for (int angle = 0; angle <= 180; angle += 1) {
   myservo.write(angle); 
   delay(50);  
 }
   //delay(100);  
 
 for (int angle = 180; angle >= 0; angle -= 1) {
   myservo.write(angle); 
   delay(50);  
 }

 //delay(100); 
}