addCar(carType) {
    const isBigCarAvailable = (carType === 1 && this.isBigRemaining > 0); 
    if(isBigCarAvailable) {
        this.isBigRemaining -= 1;
        return true;
    }
    const isMediumCarAvailable = (carType === 2 && this.isMediumRemaining > 0);
    if(isMediumCarAvailable) {
        this.isMediumRemaining -= 1;
        return true;
    }
    const isSmallCarAvailable = (carType === 3 && this.isSmallRemaining > 0);
    if(isSmallCarAvailable) {
        this.isSmallRemaining -= 1;
        return true;
    }
    return false;
  }
Time O(1) | Space O(1)
@param {number} carType
@return {boolean}