获取或创建函数/方法

以你为例,我的方法是:

#Returns a tuple where the first item is "False" if the email already exists in database, 
#and "True" if it doesn't and it was appended to the database. The second item is the email.

def get_or_create_customer (email , database): #email as String, database as list
    if email in database:
        return (False, email)
    else:
        database.append(email)
        return (True, email)

测试代码:

database = ["hello@gmail.com"]

print (get_or_create_customer("hello@gmail.com", database), database)
>> (False, 'hello@gmail.com') ['hello@gmail.com']

print (get_or_create_customer("example@gmail.com", database), database)
>> (True, 'example@gmail.com') ['hello@gmail.com', 'example@gmail.com']