无法从getter方法获取值

我刚开始学蟒蛇。由于某些性能问题,我不得不在我的AWS lambda函数中把所有代码从Java转换到Python。我正在使用lambda控制台提供的ide。

目前,我有点困在python中的类上。我读了很多教程,我认为我在setters和getter方法上所做的是正确的。这是我的代码:

class User:
    def __init__(self, user):
        self.username = user

    def get_username(self):
        return self.username

    def set_username(self, user):
        self.username = user

def lambda_handler(request, context):
    user = User("thisisaname")
    print("name of user is " + user.get_username)
    user.set_username("whatever")
    print("name of user is " + user.get_username)
    return "executed"

当lambda_处理程序被调用时,我希望输出是

name of user is thisisname
name of user is whatever

但是,当我打印user.get_username的值时。类型错误被抛出。以下是我得到的错误消息:

{   "errorMessage": "can only concatenate str (not \"method\") to str",   "errorType": "TypeError",   "stackTrace": [
    "  File \"/var/task/lambda_function.py\", line 28, in lambda_handler\n    print(\"name of user is \" + user.get_username)\n" ] }

当我用str(user.get_username)包装它时,将打印方法描述。

name of user is <bound method User.get_username of <lambda_function.User object at 0x7f4d6a4cc4d0>> 
name of user is <bound method User.get_username of <lambda_function.User object at 0x7f4d6a4cc4d0>>