Day 3: The Illuminated Path

const int ledPin1 = 8;      // the number of the first LED pin
      const int ledPin2 = 9;      // the number of the second LED pin
      const int ledPin3 = 10;     // the number of the third LED pin

      void setup() {
        pinMode(ledPin1, OUTPUT);  // initialize the first LED pin as an output
        pinMode(ledPin2, OUTPUT);  // initialize the second LED pin as an output
        pinMode(ledPin3, OUTPUT);  // initialize the third LED pin as an output
      }

      void loop() {
        digitalWrite(ledPin1, HIGH);  // turn the first LED on
        delay(500);                   // wait for half a second
        digitalWrite(ledPin1, LOW);   // turn the first LED off

        digitalWrite(ledPin2, HIGH);  // turn the second LED on
        delay(500);                   // wait for half a second
        digitalWrite(ledPin2, LOW);   // turn the second LED off

        digitalWrite(ledPin3, HIGH);  // turn the third LED on
        delay(500);                   // wait for half a second
        digitalWrite(ledPin3, LOW);   // turn the third LED off
      }