//here you can change speed of the effect, it can be faster or slower, as you wish
int time_between_blinks = 50;
void setup() {

  //here we are setting up all pins as an outputs for LEDs
  pinMode(0, OUTPUT);
  pinMode(1, OUTPUT);
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);

}

void loop() {
  //thats the for loop, the first parameter is a value that is equal to 0, the loop 
  //will work as long as the value of a will be higher or equal to 10 (second parameter)
  //and at the end we are incrementing a by 1
  int volume = analogRead(A0);
  volume = map(volume, 0, 1023, 0, 10);
  for(int a = 0; a <10; a++){
    if(volume >= a){
      digitalWrite(a, HIGH);
    }else{
      digitalWrite(a, LOW);                                                                             
    }
  }
}
 
// potentiometer is connected to A0 anolog input as its value changes ,the output of PwM also changes