设计一个书类Book能够保存书名、定价所有书的本数和总价。

class Book: def init(self, title, price, quantity): self.title = title self.price = price self.quantity = quantity self.total_price = price * quantity

def get_title(self):
    return self.title

def get_price(self):
    return self.price

def get_quantity(self):
    return self.quantity

def get_total_price(self):
    return self.total_price

def set_title(self, title):
    self.title = title

def set_price(self, price):
    self.price = price
    self.total_price = price * self.quantity

def set_quantity(self, quantity):
    self.quantity = quantity
    self.total_price = self.price * quantity

def __str__(self):
    return f"{self.title} - {self.quantity}本，单价{self.price}元，总价{self.total_price}元。