探索 python 可迭代对象的本质

>>> class MyList(object):
... def __init__(self):
...  self.container = []
... def add(self, item):
...  self.container.append(item)
... def __iter__(self):
... """返回⼀个迭代器"""
... # 我们暂时忽略如何构造⼀个迭代器对象
...  pass
...
>>> mylist = MyList()
>>> from collections import Iterable
>>> isinstance(mylist, Iterable)
True
>>>
# 这回测试发现添加了__iter__⽅法的mylist对象已经是⼀个可迭代对象了