do testu snake

int speed = 100;
bool dosnake = false;

void setup() {
  pinMode(4, OUTPUT); //lewa
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT); //prawa

  pinMode(8, INPUT);
  pinMode(9, INPUT); //fire button
  pinMode(10, INPUT);
}

void loop() {
  while (dosnake == true) {
    snake();
    if (digitalRead(9) == HIGH) {
      dosnake = false;
    }
    else if (digitalRead(10) == HIGH) {
      if (millis()%50 == 0) {
        speed -= 10;
      }
    }
    else if (digitalRead(8) == HIGH) {
      if (millis()%50 == 0) {
        speed += 10;
      }
    }
  }

  if (digitalRead(9) == HIGH and dosnake == false) {
   dosnake = true;
  }
}

int snake() {
    for(int i = 4; i < 8; i++) {
      digitalWrite(i, HIGH);
      delay(speed);
    }
    for(int j = 4; j < 8; j++) {
      digitalWrite(j, LOW);
      delay(speed);
    }
}