text: 'use strict';
  const common = require('../common');
  const stream = require('stream');
  const util = require('util');
  
  function Writable() {
    this.writable = true;
    stream.Writable.call(this);
    this.prependListener = undefined;
  }
  util.inherits(Writable, stream.Writable);
  Writable.prototype._write = function(chunk, end, cb) {
    cb();
  };
  
  function Readable() {
    this.readable = true;
    stream.Readable.call(this);
  }
  util.inherits(Readable, stream.Readable);
  Readable.prototype._read = function() {
    this.push(null);
  };
  
  const w = new Writable();
  w.on('pipe', common.mustCall(function() {}));
  
  const r = new Readable();
  r.pipe(w);
  