void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(7, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(5, OUTPUT);
 
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(7, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(100);    
  digitalWrite(6, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(100);   
  digitalWrite(5, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(100);               // wait for a second
  digitalWrite(7, LOW);   // turn the LED off by making the voltage LOW
  delay(100);   
                        // wait for a second
  digitalWrite(6, LOW);   // turn the LED off by making the voltage LOW
  delay(100); 
                        // wait for a second
  digitalWrite(5, LOW);   // turn the LED off by making the voltage LOW
  delay(100); 
     
  
                // wait for a second
}