class Billing{
    User user,
    List<Items> items,
    Payment payment
    
    public void createUser(user){
        // check if user is already there or not, if user is already created then we will use existing userId
    }
    
    public float createBill(userId,items){
        float total=0
        for(int i=0;i<items.length;i++){
            total+=items[i].price*items[i]*quantity
        }
        return total
    }
}

class User {
    int id,
    String Name,
    int phoneNo
}

class Items{
    int id,
    Category category
    float price,
    int quantity
}

enum Category{
    KIDS,SPORTS,PANTRY
}

class Payment{
    PaymentType type,
    PaymentStatus status
    public bool doPayment(typeOfPayment){
        
    }
}

enum PaymentStatus{
    DONE,PENDING
}

enum PaymentType{
    CASH,UPI,DEBIT_CARD,CREDIT_CARD
}