manage the Vary header of a HTTP response - Node.js module

 This package provides a simple module to manage the fields
 of the Vary header in a HTTP response.
 .
 The Vary HTTP response header determines how to match future
 request headers to decide whether a cached response can be
 used rather than requesting a fresh one from the origin server.
 It is used by the server to indicate which headers it used when
 selecting a representation of a resource in a content negotiation
 algorithm.
 .
 Node.js is an event-based server-side JavaScript engine.