like a passthrough, but in both directions
npm install duplex-passthroughFor when a single passthrough stream is not enough.
``javascript`
var dp = new DuplexPassThrough(stream, options);
Or, if the stream is not available yet:
`javascript
var dp = new DuplexPassThrough(null, options);
// some time later..
dp.wrapStream(stream);
``
This is useful if you have to buffer up both sides of a duplex stream
for some reason, like if you want to read some bits of a socket, but
then send it somewhere else, or do other crazy stuff.