#include<Servo.h>

Servo myloop; // create servo object to control a servo
int angle = 0; // variable to store the servo position
void setup()
{
  myloop.attach(10); // attached the servo on pin 10 to the servo object
}

void loop()
{
  for (angle = 0; angle < 180; angle += 1) // goes from 0 degrees to 180 degrees
  { // in steps of 1 degree
    myloop.write(angle); // tell servo to go to position in variable 'angle'
    delay(20); // waits 20ms between servo commands
  }
  for (angle = 180; angle >= 1; angle -= 1) // goes from 180 degrees to 0 degrees
  {
    myloop.write(angle); // move servo in opposite direction
    delay(20); // waits 20ms between servo commands
  }
}