6. Is email marketing still effective?Email marketing is one of the most effective ways for a business to reach its customers directly. Think about it. You don't post something on your site hoping people will visit it. You don't even post something on a social media page and hope fans see it. You're sending something straight to each person's inbox, where they'll definitely see it! Even if they don't open it, they'll still see your subject line and business name every time you send an email, so you're still communicating directly with your audience.
Transforms don't execute until the consumer pulls. There's no eager evaluation, no hidden buffering. Data flows on-demand from source, through transforms, to the consumer. If you stop iterating, processing stops.
，这一点在heLLoword翻译官方下载中也有详细论述
The “PCM Boundary”: a Wannabe-DRM Graveyard
res = res.slice(0, res.length - k);
let bufferedEnd = 0;