想问一下这一段跑出来结果为啥会有一个none?

class User:
def init(self, first_name, last_name):
self.first = first_name
self.last = last_name
self.login_attempts = 0

def describe_user(self):
    long_name = f"{self.first} {self.last} "
    return long_name.title()

def greet_user(self):
    print(f"Hello, {self.first} {self.last}!How are you?")
    print('\n')

def increment_login_attempts(self, numbers):
    self.login_attempts += numbers

def reset_login_attempts(self, number):
    self.login_attempts = number

def login_attempt_times(self):
    print(f"{self.login_attempts}")

user = User('kai', 'hu')
print(user.greet_user())

那里?

函数greet_user()中有一个回车行，如果你直接写user.greet_user()，就不会有空值，如果写了print就会有。