求问 这个模块是什么意思，一直看不懂。初学python求指教啊

def singleton(cls):
    instances = {}
    def get_instance():
        if cls not in instances:
            instances[cls] = cls()
        return instances[cls]
    return get_instance

@singleton
class Mylogger:

    _fpath = 'mokey.log'
    _file = None

    def __init__(self):
        self._file = open(self._fpath, mode='w',encoding = 'utf-8')
        print("初始化成功")

    def write(self, string):
        if self._file:
            self._flie.write(string)
            print("打印成功了")