int ledmerah = 4; 
int ledkuning = 7;  
int ledhijau = 8;

void setup() {
 pinMode(ledmerah, OUTPUT);
 pinMode(ledkuning, OUTPUT);
 pinMode(ledhijau, OUTPUT);
}
void loop() {
 digitalWrite(ledmerah,HIGH);
 digitalWrite(ledkuning,HIGH);
 digitalWrite(ledhijau,HIGH);
 delay(1000);

 digitalWrite(ledmerah,LOW);
 digitalWrite(ledkuning,LOW);
 digitalWrite(ledhijau,LOW);
 delay(1000);
 
}