Looks like code repetiton

[janus]

I noticed a pattern that's a bit hard to understand:

cm.channelsMutex.Lock()
	channel, exists = cm.channels[name]
	cm.channelsMutex.Unlock()

	if !exists {
		// Ensure we update our cache of known channels
		cm.channelsMutex.Lock()
		defer cm.channelsMutex.Unlock()

		channel, exists = cm.channels[name]
		if exists {
			return channel, nil
		}

		channel, err = cm.newChannel(name)
		if err != nil {
			return nil, err
		}

		cm.channels[name] = channel
	}```
What is the work of the second `cm.channels[name]` if the first  has exists false?
NB: getChannel function inside channel_manager.go file