int gassensor = 2;
int RGBBlue = 13;
int RGBGreen = 15;
int RGBRed = 18;
void setup() {
  
  Serial.begin(9600);
 pinMode(13, OUTPUT);
 pinMode(18, OUTPUT);
 pinMode(15, OUTPUT);
}

void loop() {
 int value = analogRead(2);
Serial.println(value);
delay(500);
if(value == 0)
{
digitalWrite(RGBRed, HIGH);
}
 if(value <= 10)
{
digitalWrite(RGBBlue, HIGH);
}
 if(value <= 500)
{
digitalWrite(RGBGreen, HIGH);
}
 if(value > 500)
{
  digitalWrite(RGBBlue, HIGH);
  digitalWrite(RGBRed, HIGH);
}
}