1. what are iterators? an iterator is an object that can be iterated (looped) over. it uses __iter__() to return itself and __next__() to move through elements. example: numbers = [1, 2,...
迭代器是可循环对象，使用__iter__()和__next__()方法。生成器通过yield逐个生成项，节省内存，适合处理大数据。生成器表达式提供简洁语法，类似列表推导，提升代码效率和可扩展性。
