code: func NewChannelEntry(c chan struct{}) (Entry, chan struct{}) {
  	if c == nil {
  		c = make(chan struct{}, 1)
  	}
  
  	return Entry{Context: c, Callback: &channelCallback{}}, c
  }
docs: // NewChannelEntry initializes a new Entry that does a non-blocking write to a
  // struct{} channel when the callback is called. It returns the new Entry
  // instance and the channel being used.
  //
  // If a channel isn't specified (i.e., if "c" is nil), then NewChannelEntry
  // allocates a new channel.