var stream = require('stream') function isStream (obj) { return obj instanceof stream.Stream } function isReadable (obj) { return isStream(obj) && typeof obj._read == 'function' && typeof obj._readableState == 'object' } function isWritable (obj) { return isStream(obj) && typeof obj._write == 'function' && typeof obj._writableState == 'object' } function isDuplex (obj) { return isReadable(obj) && isWritable(obj) } module.exports = isStream module.exports.isReadable = isReadable module.exports.isWritable = isWritable module.exports.isDuplex = isDuplex