Working with a Micro Servo

1#include <Servo.h>
2
3int i = 0;
4
5int j = 0;
6
7int k =  0;
8
9Servo servo_3;
10
11void setup()
12{
13  servo_3.attach(3);
14
15}
16
17void  loop()
18{
19  for (i = 0; i <= 120; i += 1) {
20    servo_3.write(i);
21    delay(50);  // Wait for 50 millisecond(s)
22  }
23  for (k = 120; k >= 0; k -= 1) {
24    servo_3.write(k);
25    delay(50); // Wait for 50 millisecond(s)
26  }
27}