Python类方法的示例用例是什么？

Python类方法的示例用例是什么？

初始化的辅助方法：

class MyStream(object):    @classmethod    def from_file(cls, filepath, ignore_comments=False): with open(filepath, 'r') as fileobj: for obj in cls(fileobj, ignore_comments):     yield obj    @classmethod    def from_socket(cls, socket, ignore_comments=False):        raise NotImplemented # Placeholder until implemented    def __init__(self, iterable, ignore_comments=False):       ...