Node.js Transform stream piping, order, asynchronous, wtf

dunno.js

var stream = require('readable-stream');
var Transform = stream.Transform;
var util = require('util');
var _ = require('lodash');
var $ = require('chalk')

// Just serialize a object stream into lines of JSON
function Serializer() {
  Transform.call(this, {objectMode: true});
}
Serializer.prototype = Object.create(Transform.prototype, {constructor: {value: Serializer}});
Serializer.prototype._transform = function(chunk, encoding, done) {
  done(null, $.green(JSON.stringify(chunk)) + '\n');
};

// For each "log" method call, output an object. Allow indentation to be
// increased and decreased. For any logger piped into this logger, increment
// indentation cumulatively.
var counter = 0;
function Log(name, options) {
  Transform.call(this, {objectMode: true});
  this.name = name;
  this.indent = 0;
}
Log.prototype = Object.create(Transform.prototype, {constructor: {value: Log}});
Log.prototype._transform = function(chunk, encoding, done) {
  console.log('[%s] %s', this.name, '_transform');
  var obj = _.extend({}, chunk);
  obj.indent += this.indent;
  done(null, obj);
};
Log.prototype.group = function() {
  console.log('[%s] %s', this.name, 'group');
  this.indent++;
};
Log.prototype.groupEnd = function() {
  console.log('[%s] %s', this.name, 'groupEnd');
  this.indent--;
};
Log.prototype.log = function(message) {
  console.log('[%s] %s "%s"', this.name, 'log', message);
  this.push({
    counter: ++counter,
    logger: this.name,
    message: message,
    indent: this.indent,
  });
};

// Create parent logger that will be serialized and output to stdout.
var parent = new Log('parent');
parent.pipe(new Serializer).pipe(process.stdout);

// Create child logger that will be passed through the parent logger,
// so that indentation can (theoretically) be accumulated, then serialized
// and output to stdout.
var child = new Log('child');
child.pipe(parent);

parent.log('indent should be 0');
child.log('indent should stay at 0');
parent.group();
parent.log('indent should be 1');
child.log('indent should go from 0→1');
child.group();
parent.log('indent should be 1');
child.log('indent should go from 1→2');
child.groupEnd();
parent.log('indent should be 1');
child.log('indent should go from 0→1');
parent.groupEnd();
child.group();
parent.log('indent should be 0');
child.log('indent should stay at 1');
child.groupEnd();

output.txt

[parent] log "indent should be 0"
[child] log "indent should stay at 0"
[parent] group
[parent] log "indent should be 1"
[child] log "indent should go from 0→1"
[child] group
[parent] log "indent should be 1"
[child] log "indent should go from 1→2"
[child] groupEnd
[parent] log "indent should be 1"
[child] log "indent should go from 0→1"
[parent] groupEnd
[child] group
[parent] log "indent should be 0"
[child] log "indent should stay at 1"
[child] groupEnd
{"counter":1,"logger":"parent","message":"indent should be 0","indent":0}
{"counter":3,"logger":"parent","message":"indent should be 1","indent":1}
{"counter":5,"logger":"parent","message":"indent should be 1","indent":1}
{"counter":7,"logger":"parent","message":"indent should be 1","indent":1}
{"counter":9,"logger":"parent","message":"indent should be 0","indent":0}
[parent] _transform
{"counter":2,"logger":"child","message":"indent should stay at 0","indent":0}
[parent] _transform
{"counter":4,"logger":"child","message":"indent should go from 0→1","indent":0}
[parent] _transform
{"counter":6,"logger":"child","message":"indent should go from 1→2","indent":1}
[parent] _transform
{"counter":8,"logger":"child","message":"indent should go from 0→1","indent":0}
[parent] _transform
{"counter":10,"logger":"child","message":"indent should stay at 1","indent":1}

package.json

{
  "name": "dunno",
  "version": "0.0.0",
  "dependencies": {
    "lodash": "~1.3.1",
    "chalk": "~0.2.0",
    "readable-stream": "~1.0.15"
  }
}