def get_discount(level):
    if level == 1:
        "大量計算代碼"
        discount = 0.1
    elif level == 2:
        "大量計算代碼"
        discount = 0.2
    elif level == 3:
        discount = 0.3
    elif level == 4:
        discount = 0.4
    elif level == 5:
        discount = 0.5
    elif level == 6:
        discount = 3 + 2 - 5 * 0.1
    else:
         return '等級錯誤'
    return discount

def parse_level_1():
    "大量計算代碼"
    discount = 0.1
    return discount

def parse_level_2():
    "大量計算代碼"
    discount = 0.2
    return discount

def parse_level_3():
    "大量計算代碼"
    discount = 0.3
    return discount

def parse_level_4():
    "大量計算代碼"
    discount = 0.4
    return discount

def parse_level_5():
    "大量計算代碼"
    discount = 0.5
    return discount

def parse_level_6():
    "大量計算代碼"
    discount = 3 + 2 - 5 * 0.1
    return discount

discount_map = {
 1: parse_level_1,
  2: parse_level_2,
  3: parse_level_3,
  4: parse_level_4,
  5: parse_level_5,
  6: parse_level_6,
}

discount = discount_map.get(level, '等級錯誤')

@value_dispatch
def get_discount(level):
    return '等級錯誤'

@get_discount.register(1)
def parse_level_1(level):
    "大量計算代碼"
    discount = 0.1
    return discount

@get_discount.register(2)
def parse_level_2(level):
    "大量計算代碼"
    discount = 0.2
    return discount

@get_discount.register(3)
def parse_level_3(level):
    "大量計算代碼"
    discount = 0.3
    return discount

@get_discount.register(4)
def parse_level_4(level):
    "大量計算代碼"
    discount = 0.4
    return discount

@get_discount.register(5)
def parse_level_5(level):
    "大量計算代碼"
    discount = 0.5
    return discount

@get_discount.register(6)
def parse_level_1(level):
    "大量計算代碼"
    discount = 3 + 2 - 5 * 0.1
    return discount


discount = get_discount(3)
print(f'等級3的用戶，獲得的折扣是：{discount}')

@get_discount.register(2)
@get_discount.register(3)
def parse_level_2(level):
    "大量計算代碼"
    discount = 0.2
    return discount