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+# common-streams
+
+[![Build Status](https://travis-ci.org/blockai/common-streams.svg?branch=master)](https://travis-ci.org/blockai/common-streams)
+
+A collection of useful streams.
+
+## Install
+
+```bash
+npm install --save common-streams
+```
+
+Requires Node v6+
+
+## Usage
+
+See [./test](./test) directory for more usage examples.
+
+Example:
+
+```javascript
+import { HashStream, SizeStream } from 'common-streams'
+import concat from 'concat-stream'
+
+const rs = getReadStream() // e.g. fs.createReadStream(...)
+const ws = getWriteStream() // e.g. fs.createWriteStream(...)
+
+const sha1Stream = new HashStream('sha1')
+const sizeStream = new SizeStream()
+
+rs.pipe(sha1Stream).pipe(concat(([{ digest }]) => {
+  console.log(digest, '=', '4129def2ea7cb7945ddfbb785969898fca2e34c3')
+}))
+rs.pipe(sizeStream).pipe(concat(([{ size }]) => {
+  console.log(size, '=', 2447774)
+}))
+rs.pipe(ws)
+```
+
+### HashStream
+
+Transform stream that operates in object mode and returns a single `{ digest: 'hash digest' }` object.
+
+`new HashStream(algorithm, [, opts])`
+
+**algorithm**: any algorithm supported by [crypto.createHash](https://nodejs.org/api/crypto.html#crypto_crypto_createhash_algorithm)
+
+**opts.encoding**: any encoding supported by [hash.digest](https://nodejs.org/api/crypto.html#crypto_hash_digest_encoding). Defaults to `hex`.
+
+### SizeStream
+
+Transform stream that operates in object mode and returns a single `{
+size: 1000 }` object where the size is an integer representing the total
+size in bytes of the stream.
+
+`new SizeStream()`
+
+If passed a callback `new SizeStream(cb)` it will just act as a
+PassThrough stream and call the callback when it's done.
+
+### RandomStream
+
+`new RandomStream(max)`
+
+Readable stream that emits `max` random bytes before ending.
+
+### DiscardStream
+
+`new DiscardStream(start)`
+
+Swallows all bytes until `start` is reached.
+
+### MeterStream
+
+`new MeterStream(max)`
+
+See [meterstream](https://github.com/blockai/meterstream)