arduino internal pull up resistor

1pinMode(2,INPUT_PULLUP);

1void setup() {
2  pinMode(13, OUTPUT);    // sets the digital pin 13 as output
3}
4
5void loop() {
6  digitalWrite(13, HIGH); // sets the digital pin 13 on
7  delay(1000);            // waits for a second
8  digitalWrite(13, LOW);  // sets the digital pin 13 off
9  delay(1000);            // waits for a second
10}

1Serial.println(sensorValue, DEC);

1pinMode(13, OUTPUT);

1Serial.begin(9600);

1int sensorValue = digitalRead(2);