#include <Servo.h>

Servo mysevo;  // create servo object to control a servo
// twelve servo objects can be created on most boards

int pos = 0;   // variable to store the servo position

void setup() {
   mysevo.attach(9);  //attaches the servo on pin 9 to the servo object
}

void loop() {
  for(pos = 0; pos <= 180; pos += 1) {//goes from 0 degrees to 180 degrees
  // in steps of 1 degree
    mysevo.write(pos);
  delay(15);
 }
 for (pos=180;pos >= 0;pos -= 1){//goes from 180 degrees to 0 degrees 
   mysevo.write(pos);
  delay(15);
 }
}