code: public function setChannel($channel, LoggerInterface $logger)
  	{
  		if (isset($this->channels[$channel])) {
  			throw new InvalidArgumentException("Channel $channel is already defined");
  		}
  
  		$this->channels[$channel] = $logger;
  	}
docs: Set a channel instance.
  
  @param string          $channel
  @param LoggerInterface $logger
  
  @throws InvalidArgumentException If the channel is already defined.