int led1 = 2; 
int led2 = 3; 
int led3 = 4; 
int led4 = 5; 
void setup()
{
pinMode(led1, OUTPUT); 
pinMode(led2, OUTPUT); 
pinMode(led3, OUTPUT); 
pinMode(led4, OUTPUT); 
 Serial.begin(9600); 
 Serial.flush();
} 
void loop()
{
String input = "";
while (Serial.available() > 0)
{
input += (char) Serial.read();
delay(5); // ini buat jedanya gan satuannya millisecond
}
on:
if (input == "1")
{
digitalWrite(led1, HIGH); // menghidupkan led, ini pake aktif high
Serial.println("LAMPU 1 NYALA");
loop();
goto on;
}

off:
if (input == "2")
{
digitalWrite(led1, LOW); // mematikan led
Serial.println("LAMPU 1 MATI");
loop();
goto off;
}

all:
if (input == "3")
{
digitalWrite(led1, HIGH); // mematikan led
digitalWrite(led2, HIGH);
digitalWrite(led3, HIGH);
digitalWrite(led4, HIGH);
Serial.println("SEMUA LAMPU NYALA ");
loop();
goto all;
}

offall:
if (input == "4")
{
digitalWrite(led1, LOW); // mematikan led
digitalWrite(led2, LOW);
digitalWrite(led3, LOW);
digitalWrite(led4, LOW);
Serial.println("SEMUA LAMPU MATI");
loop();
goto offall;
}

flip:
if (input == "5")
{
digitalWrite(led4, HIGH);
digitalWrite(led3, HIGH);
digitalWrite(led2, HIGH);
digitalWrite(led1, HIGH);
delay(500);
digitalWrite(led4, LOW);
digitalWrite(led3, LOW);
digitalWrite(led2, LOW);
digitalWrite(led1, LOW);
delay(500);
Serial.println("FLIP-PLOP");
loop();
goto flip;
}

running:
if (input == "6")
{
 digitalWrite(led1, HIGH);
  delay(100);
  digitalWrite(led2, HIGH);
  delay(100);
  digitalWrite(led3, HIGH);
  delay(100);
  digitalWrite(led4, HIGH);
  delay(100);
   digitalWrite(led1, LOW);
  delay(100);
  digitalWrite(led2, LOW);
  delay(100);
  digitalWrite(led3, LOW);
  delay(100);
  digitalWrite(led4, LOW);
  delay(100);
Serial.println("RUNNING LED");
loop();
goto running;
}
}