code: func SetDefaultInfoStream(infoStream InfoStream) {
  	log.Print("Setting default infoStream...")
  	defaultInfoStreamLock.Lock() // synchronized
  	defer defaultInfoStreamLock.Unlock()
  	assert2(infoStream != nil, `Cannot set InfoStream default implementation to nil.
  To disable logging use NO_OUTPUT.`)
  	defaultInfoStream = infoStream
  }
docs: /*
  Sets the default InfoStream used by a newly instantiated classes. It
  cannot be nil, to disable logging use NO_OUTPUT.
  */