Async tools and when() implementation for Node.js

 A lightweight Promises/A+ and when() implementation, plus other
 async tools.
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 A when() function is responsible of triggering actions depending on the
 result of executing asynchronous actions, with submethods to check for
 any or all results, and handling exceptions.
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 Promises/A+ is a programming interface for asynchronous operations.
 .
 Node.js is an event-based server-side JavaScript engine.