void setup () {
  // put your setup code here, to run once:
pinMode(13, OUTPUT);
pinMode(11, OUTPUT );
pinMode(7, OUTPUT );
}

void loop () {
  // put your main code here, to run repeatedly:
digitalWrite (13, HIGH );              
digitalWrite (11, LOW );
digitalWrite (7, LOW );
delay(200);
digitalWrite (13, LOW );
digitalWrite (11, HIGH );
digitalWrite (7, LOW );
delay(200);
digitalWrite (13, LOW );
digitalWrite (11, LOW );
digitalWrite (7, HIGH );
delay(200);
digitalWrite (13, LOW );
digitalWrite (11, HIGH );
digitalWrite (7, LOW );
delay(200);
}