is-pull-stream
check what sort of pull-stream a thing is.
api
isSource (stream)
return true if stream is a source.
isSink (stream)
return true if stream is a sink.
isDuplex (stream)
return true if stream is a duplex steam.
through
a through stream is a sink that returns a source, so don't know if it's not a sink until you pass a source to it.
License
MIT