def join(channel, key = nil)
      channel = Channel(channel)
      channel.join(key)

      channel
    end
def join(channel, key = nil)
      channel = Channel(channel)
      channel.join(key)

      channel
    end
@endgroup
 @group Channel Control
 Join a channel.

 @param [String, Channel] channel either the name of a channel or a {Channel} object
 @param [String] key optionally the key of the channel
 @return [Channel] The joined channel
 @see Channel#join