int l = 2;
int b = 7;
int v = 0;

void setup() {
  // put your setup code here, to run once:
  pinMode(l, OUTPUT);
  pinMode(b, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  v=digitalRead(b);
  if (v==HIGH){
    digitalWrite(l, HIGH);
  }else{
    digitalWrite(l, LOW);
  }
}