#include <Servo.h>

Servo servo;
int angle = 10;

void setup() {
  servo.attach(8);
  servo.write(angle);
  pinMode(12, OUTPUT);
  pinMode(13, OUTPUT);
}


void loop()
{
  digitalWrite(13, HIGH);
  digitalWrite(12, LOW);
  delay(500);
  digitalWrite(13,LOW);
  digitalWrite(12,HIGH);
  delay(500);

  for(angle = 20; angle < 135; angle++)
  {
    servo.write(angle);
    delay(30);
  }

  for(angle = 135; angle > 20 ; angle--)
  {
    servo.write(angle);
    delay(30);
  }
}