#include <Servo.h>
Servo leftServo;
#define SERVO_PIN 9
int start = 90;

void setup() {
  leftServo.attach(SERVO_PIN);
  leftServo.write(start);
  delay(1000);
}

void loop() {
  for (int direction = 0; direction < 2; direction++) {
    for (int degree = 0; degree < 180; degree += 15) {
      if (direction == 0)
        leftServo.write(degree);
      else
        leftServo.write(180 - degree);
      delay(250);
    }
  }
}