streaming pipeline with a mutable configuration and labels

 This modules allows one to create a pipeline duplex stream given an
 array of streams. Each stream will be piped to the next.
 .
 Streams could also be added and removed dynamically at runtime.
 Every stream could be associated with a string (label).
 .
 This a dependency of browserify. Browserify is a javaScript tool that allows
 developers to write Node.js-style modules that compile for use in the browser.
 .
 Node.js is an event-based server-side JavaScript engine