The Readable operators (map, filter, forEach, toArray, some, find, every,
flatMap, drop, take, reduce) run over string and Buffer chunk streams with
Node's ordering, errors, and concurrency, highWaterMark and signal options.
Readable.from reads arrays lazily and accepts the objectMode and
highWaterMark options, and its JavaScript form follows from.js's checks.
stream.compose returns a Duplex over a pipeline of stream instances.
pipeline now follows pipeline.js: per-stream destroyers and eos watchers,
and the callback on a tick once every watcher finished. 'finish' waits for
a pending _final or _flush callback, and a failed synchronous write emits
'error' one tick later, as in Node.