// Setting up pins D0 and D1
void setup() {
  pinMode(D0, OUTPUT); // sets pin D0 as an output
  pinMode(D1, INPUT);  // sets pin D1 as an input
}

// Main program loop
void loop() {
  estado = digitalRead(D1); // reads the state of pin D1 and stores it in 'estado'
  
  if (estado == HIGH) {
    digitalWrite(D0, HIGH); // sets pin D0 HIGH if the state of D1 is HIGH
  } else {
    digitalWrite(D0, LOW); // sets pin D0 LOW if the state of D1 is not HIGH
  }
}