int led1= 10;
int led2= 11;
int led3= 12;
void setup() {
  // put your setup code here, to run once:
   pinMode(led1, OUTPUT);
   pinMode(led2, OUTPUT);
   pinMode(led3, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  
  digitalWrite(led1, HIGH);
  delay(1000);
  digitalWrite(led2, HIGH);
  delay(1000);
  digitalWrite(led3, HIGH);
  delay(1000);
  digitalWrite(led1, LOW);
  delay(1000);
  digitalWrite(led2, LOW);
  delay(1000);
  digitalWrite(led3, LOW);
  delay(1000);

}