code: func (m *ChannelDeMultiplexer) Close() {
  	m.lock.Lock()
  	defer m.lock.Unlock()
  	m.closed = true
  	for _, ch := range m.channels {
  		close(ch.ch)
  	}
  	m.channels = nil
  }
docs: // Close closes this channel, which makes all channels registered before
  // to close as well.